AQUACUTURE NOTE pdf.pdf

Compile by Dr. Manoj karki (B.V.Sc&A.H)
Based on the syllabus of Diploma in Veterinary Science (I. SC vet) 2nd
year
(Council for Technical Education and Vocational Training) CTEVT
A Hand Book of
Fisheries Science and Aquaculture
Compiled by: Dr. Manoj karki
B.V.Sc & A.H
2022/8/23

Content:
Unit: 1 introduction
Unit2: River and Lake Fisheries
Unit 3: Pond fish Culture
Unit 4: Fish breeding
Unit 5: Live fish transportation
Unit 6: Common fish disease and parasite
Unit 7: Marketing of Fish

UNIT: 1 AQUUACULTURE INTRODUCTION
Date: 2022/8/16
Indigenous and Exotic Breed of Fish in Nepal
• A native fish species that is indigenous to a specific place or specific
regions which are favorable and suitable to that environment and exist
from a long period of time is known as indigenous fish species.
• In general, the fish which are cultivated in specific area or region since
very long time is known as indigenous fish species to that region or area.
• Followings are the indigenous fish species of Nepal:
• Rohu (Labeo rohita)
• Naini (Cirrhinus mrigla)
• Bhakur (Catla catla)
• Sahar (Tor tor)
About 217 species are found in Nepal. Rohu, bhakur, naini, sahar, katla are
commercially farming in Nepal
Rohu (Labeo rohita)
 Body is elongated and cylindrical, small pointed head, sub terminal
mouth and one pair of maxillary barbells.
 The lips are thick and fringed
 Body is fully covered with scale on maturity and it is slightly reddish on
the sides and whitish on belly
 They are bottom and column feeder
 Feed on plants including decaying vegetation.
 Food of this includes periphytons, planktonic and filamentous algae,
rotting vegetation etc..
 Length 1 m, weight 30 kg

 Breeding season June to August where the temperature is 25-30 degree
Celsius
Bhakur/ Catla (Catla catla)
 it is fast growing fish among the indigenous cultivated carps
 The barbells are absent, large upturn mouth
 Body color is grayish to silvery on upper sides and whitish on belly
 It is surface zooplankton feeder but young one feed both zooplankton
and phytoplankton
 It attains 1-1.5 kg in 1st
year over 1m of length and size upto 45 kg
 The breeding season is June to August when the temperature is 25-30
degree Celsius

Naini/ Mirgal (Cirrhinus mrigla)
 It is most important fish after rohu and catla for culture
 It is elongated and cylindrical body
 Small head and sub terminal mouth, one pair of small barbells are present
 It is bottom feeder, omnivorous in nature and feeds on detritus mud
organism, decaying plant and animal matter however young ones feed
on zooplankton
 Largest size attains upto 90 cm and 30 kg
 Time of maturity and breeding behavior is similar to rohu and catla
Exotic breed of fish
1. Common carp : 3 types of common carp introduce in Nepal
I. Mirror/ Isareli crap (Cyprinus carpivora speacularis)
II. German/ scale crap (Cyprinus carpivora communis)
III. Nesis carp (Cyprinus carpo)
Common carp is the most important cultivated fish in the world, which was
introduced to Nepal in 1956 and 1960 from India and Israel
Mirror/ Isareli crap (Cyprinus carpivora speacularis)

 They are omnivorous and bottom feeder
 Have irregular and patchy scaling making fish unique
 Length : 50 cm, weight upto 50 kg
 In 1 year grow up to 1 -1.5 kg
 Suitable for rice fish farming
German/ scale crap (Cyprinus carpivora communis)
 They are omnivorous and bottom feeder
 Heavy body with barbells on either side of the upper jaw
 Color varies from brassy green or yellow to golden brown
 Belly is usually yellowish white
 Dorsal fin with 17-21 rays and anal fin both have a heavy tooted spine
 Length : 12-25 inch, weight up to 18 kg

Nesis carp (Cyprinus carpo)
 Pure common carp introduce in Nepal from Iserial in 1990
 Body is flat
 Head is comparatively smaller
 They are omnivorous
 They lay egg two times in a year. I,e, summer and winter

Grass crap (Ctenopharyngodon idella)
 This is exotic crap brought in Nepal from india and japan in 1967 and
1968
 Also called white Amur in Russia
 Body elongated and cylindrical with large greenish scales ( length: 1-2
m, weight: 32 kg)
 Mouth sub terminal (upper jaw is slightly longer than lower jaw)
 Mouth is toothless but specialized pharyngeal teeth for rasping aquatic
vegetation. I,e herbivorous fish
 Barbels absent
 Breeding season is April to May when temperature is 22 -27 degree
Celsius
 Grass crap Is column/ marginal feeder, herbivorous and feed on a wide
variety of aquatic macro vegetation including terrestrial plants.

Silver crap (Hypophthalmichthys molitrix)
 Introduce in Nepal from India and japan in 1967 and 1968
 Flat and laterally compresses body covered by small silvery scales
 Length 82 cm weight 40-50 kg
 Head small, barbells absent, mouth upturned with lower jaw longer than
upper and the abdominal keel is complete.
 It is surface, phytoplankton feeder but young fry feed on zooplankton
 The breeding season is April to July when temperature is 24 -28 degree
Celsius
Big head crap (ARISTICHTHYS NOBILIS)
• This is an exotic fish introduced in Nepal from America and Hungary in
1969 and 1972
• The body of fish is flat, laterally compressed and covered by small
silvery scales brownish above

• Head long and massive, barbells absent, mouth large, upturned with
lower jaw longer than upper
• It is surface, zooplankton feeder but larvae mainly feed on unicellular
phytoplankton
• Largest size 40 -45 kg
• Artificial breeding done by hypophysation
• Breeding season is April to July with temperature 24-28 degree C
Nile tilapia (Oreochromis niloticus)
• Nile tilapia are native to most major northern and central African river
system
• First introduce in Nepal from Thailand in 1985
• This fish is characteristerized by the presence of long spiny dorsal fin,
interrupted lateral line and the presence of distinct stripes on the body
and tail
• It Is a plankton feeder, omnivorous and accept insects, formulated feed
• It can reach up to a size of 2.5 kg

• Breeding may not occur every month, but under favorable environment
condition a female will normally produce several batches of young in a
year
African cat fish (Clarias gariepinus)
• African cat fish are called ‘MANGUR’ in Nepal
• It has an unauthorized introduction to Nepal in 1990 from India
• The fish have long and cylindrical body, flat bony head and mouth with
four pair of barbells
• The fish is usually of dark grey or black coloration on the dorsal side
• It is a carnivorous but show omnivorous feeding habit
• It feed on a living as well as dead animals matters
• It is also able to survive in shallow, muddy water for long time
• Size: 20 -30 kg
• The breeding season is May to July when temperature is 25-30 degree C

Rainbow trout (Oncorhynchus mykiss)
• The rainbow trout is high valued cold water fish and is a member of
salmon family
• It is native to USA, but is now farmed globally
• It was introduced in Nepal in 1988 from japan
• The body is elongated and laterally compressed with rounded snout
• The upper side of the head is blue green, yellow green or almost brown.
• The side are silvery and marked with bright pink blush to red band and
many small black spots.
• Rambo trout is highly carnivorous. It feed on animal matter like insect,
mollusks, fish egg and small fishes etc..
• It need high protein content feed for culture
• The growth of rainbow trout in the first year is 200-300 g, which is
market size in Nepal
• The breeding season is November to January with temperature is 12-15
degree C

Pangas catfish (Pangasiodon hypophthalmus)
• Pangas is a native to the rivers of south Asia. It was introduce to Nepal
from India and has been cultivating be farmer since few years.
• The fish is commonly known as ‘PANGAS’ or ‘BAIKHI’ in Nepal
• The body of the fish is long and laterally flattened with no scales.
• Head is relatively small, mouth is broad with small sharp teeth on jaw.
• Two pair of small barbells are present, eyes are relatively large
• Large adult are uniformly grey and lack the stripping , the side are silvery
in color
• It is omnivorous and the diet mainly consists of crustaceans, small fish,,
and plant matter
• It grow better in the temperature rang of 25-30 degree C.
• The breeding season is May to July when the temperature is 25-30 degree
C.

General Morphology of Fish
Presenter: Dr. Manoj karki
(B.V.Sc & A.H)
2022/6/8
Definition of fish
Fishes are aquatic cold blooded vertebrates, which breathe by means of gills
and propelling and balancing themselves by means of fins. However, some
species are well known for their ability to leap over the sea surface and fly
some distance using their fins as wings.
Many types of aquatic animals names fish, such as shellfish, crayfish, jellyfish,
starfish and cuttle fish are not true fish.
Fisheries: The industry or occupation devoted to the catching, processing and
selling of aquatic organism from natural water resources are the fisheries
activities.
According to FAO, (1988), aquatic organism which are exploitable by the
public as common property resources with or without appropriate license are
know as fisheries. For example, Marine fisheries, riverine fisheries, lake
fisheries, etc..
The body of fish can be divided into 3 parts: head, trunk and tail. There is no
neck in fish as In the land animals. The gill opening between the head and the
trunk. Vent is the dividing lines between the trunk and the tail

Shape and size
In general, the body of fish is fusiform and streamlined but they may be
laterally compressed (eg. Flounders), depressed (eg. Rays), serpentine (eg.
Eels), filliform (snipe eel)
Compare to other body shapes, fusiform shape is quite energy efficient for
swimming.
Body shape is a good indicator of how a fish moves and where it lives.

The smallest fish in the world is the Paedocypris prgenetica (7.9 mm), found
in the Sumatra island of Indonesia
The largest fish is whale shark (Rhincodon typus) 20m
Similarly the largest fish found in Nepal is Bagarius yarelli (siluriformes,
225cm and 280kg)
Smallest fish found in Nepal: Erethestes hara (Hara hara) 2.5 cm
External organs
A) Mouth: mouth of fish is generally situated anteriorly in the head, however,
its location varies depend on species and feeding habits.
There are 3 general location of the mouth in the fish:
1. upturned or superior mouth: lower jaw is longer than upper jaw. The fish is
generally a surface feeder.
2. Terminal or sub terminal mouth: upper and lower jaw are almost equal. The
fish is generally a column feeder
3. Underslung or inferior mouth: upper jaw is longer than lower jaw. The fish
is generally a bottom feeder

B) Snout : It is that portion of the head situated in front of the eyes. The snout
has a pair of nostril or nares on each sides
C) Nostril: generally there are 2 nostrils on either side of the head (two pairs)
in fishes. They serve as olfactory organs that feel taste and smell.
It is important to note that although fish have nostrils, they play no role in the
respiration because they are not connected to the throat or gills.
D) Eyes: fish have a pair of eyes situated on the lateral sides of the head and
each having its own vision zone. Eye size and position vary depending on the
habitat and behavior of the species
There lens are spherical, a design that enables a fish to focus in water. Fish
don’t have eyelid. Because they lived in water. Fish do not sleep, but some fish
spend a good portion of their time on resting.

E) Barbells: the barbels are elongated tactile organs located closed to the
mouth, quite similar to the whiskers on a cat. The barbells are used to screen
the environment and increased awareness of its surroundings. The numbers and
size of barbells varies greatly with species.
Based on their origin, barbells are named as:
1. Maxillary barbells: arise from upper jaw
2. Mandibular barbells: arise from lower jaw
3. Rostral barbells: arise from the region of snout
4. Nasal barbell: arise from the region of nostrils

F) Operculum:
The operculum is the bony flap covering and protecting the gills. It open and
close to allow water to pass over the gills.
G) fins:
The fins are the major locomotory organs in fishes. There are two types of fins
in fish. Unpaired or medians fins and paired fins.
The unaired fins include dorsal fin on the back, an anal fin on the ventral side
behind the vent and a caudal fin at the end of the tail.
The paired fins includes pectorial and pelvic fin.
fins give stability and control the direction of movement during swimming
H) Vent: the vent is the cumulative term for the external openings of digestive,
urinary and reproductive tracts. It is generally situated on the posterior ventral
side, just in front of the anal fin. There is a separate opening for digestive tract
called anus. However, the opening for urinary and reproductive tract are
generally combined in male and separate in female. The function of the vent
are to remove waste and extra water, and to expel eggs or milt during spawing.

Scale Shape Characteristics Example illustration
Ganoid Rhombic Covered with
enamel like
layers
Gar
Cycloid Almost
circular
Smooth edges Salmon
Ctenoid Round Serrate or
combed edges
Perch
Placoid Torpendo
like pointed
ens
Sharp, tooth
like
Blue shark
Function of scale:
1. Which provides protection to the body
2. It protect the body from external injury, parasite, fungus, bacteria and
other microorganism
3. The scales are of considerable help in calculating the age and growth rate
of fishes

Tail region: the tail forms one third of the body. It is laterally compressed and
narrow behind
At the ends earing unpaired homocercal caudal fin in majority of fishes. While
in some fishes caudal fin may heterocercal or diphycercol or protocercal type.
The single unpaired and fin lies just behind the anus.
Fin rays: the fin of the fishes are supported by dermal rays or spines. The
dermal fin rays of the elasmobranch and bony fishes are known collectively as
dermatotrichia or lepidotrichia.
They may be segmented or unsegmented, branched, unbranched. The
movement of the fin are due to the action of the muscles, these movement
beings possible because of the articulation and often flexibility of these rays.
The fin ray are 2 types: soft and hard rays
In soft rays: they are thin, flexiable y shaped, segmented and branched always
biserial (two lateral components paired on the midline)
Hard rays : a number of soft rays united solidly to compose hard rays, which
are stout, rigid, unsegmented, uniserial and sharply pointed.

Function of fins:
The principal function of the fins is regarded for locomotion in the form of
progession, steering or balancing
The dorsal and anal fins do not perform the function of forward movement of
the fish. But they assist in upward and downward turning.
In some species, paired fins are used for nest building and to hold the eggs
during spawning.
Taxonomy of fishes of Nepal
Total of 185 species belonging to 93 genera under 31 families and 11 orders
have been reported in Nepal, (Shreasth 2001)
Position of fish in hierarchical system of classification:

Kingdom: Animalia
Sub-Kingdom: Metazoa
Phylum: Chordata
Sub-Phylum: Vertebrata
Division: gnathostomata
Super class: Pisces
Class: Teleostom
Order: Different orders…
Principle of aquaculture:
 Species selection and stocking of quality fish seed
 Water quality management for suitable aquatic environment
 Nutrition and feeding management
 Mono/polyculture and or integration of aquaculture with other farming
 Seed production, genetic management and stock improvement
Environmental protection
Unit 1.
Desirable character of fish for culture:
1. Should be able to live in captivity (pound, reservoirs, etc.) with other fish
without any disturbance
2. Should be able to feed on natural as well as artificial diet
3. Have high feed conversion ratio: (FCR)= feed intake (KG)/weight
gain (kg)
4. Should be herbivorous or omnivorous
5. Should be able to grow at a faster rate and attain marketable size in short
period of time
6. Should be breed successfully

7. Should be hardy and able to tolerate climatic as well as environmental or
ecological change in the cultivated water
8. Should be resistant to disease
9. Should be palatable and nutritive
Unit 2: River and Lake Fisheries
Define and classification of natural water body
River Lake
A natural stream of water is fairly
large size flowing in a definite course
or channel or series of diverging and
converging channels
A body of fresh or salt water of
considerable size, surrounding by
land
River look like snakes slithering Lakes are more like huge paddles of
water
River are moving Lakes are stationary
Classification of river based on fish zone:
1. Snow trout zone: this zone lies between 800- 3000masl and the rivers is
normally fast snowfed or glacier fed cold water. This zone is dominated
by trout.
2. Stone carp or mixed zone: this zone ranges between 1200-1800 masl
and is truly a mixed zone with still fast flowing cold water hill stream
consisting of the above fishes mixed with stone carp, catfish and trout.
3. Hill barble zone: this zone lies between 600-1200 m and the rivers have
slightly slow moving water with moderate temperature. This zone is
famous for sportive fishes like mahaseer and katle.

4. Major carp zone: this zone ranges between 150-600m mainly in the
terai. Characterize by slow and warm water with dominant fishes such
as Rohu, Mirgal.
Classification of river based on origin:
1. Himalayan river: the river which originated from the mountain
Himalayan are termed as Himalayan river. They derived their supply
from melting from of snow during the spring and summer season and
also from rains during monsoon season
2. Non Himalayan river: they originate from mountain. They supply of
water is mainly in rainy season. River practically dry up in the summer
season.
3. Flashy river: in this type of river the flood occur and recedes very
suddenly. The flood may be rise and reduces (disappear) in a short period
of one to two days.
Classification of lakes:
1. Temporary lake: lakes may exit temporarily filling up the small
depression of undulating ground after heavy shower.
2. Permanent lakes: these lakes are deep and carry more water than could
ever be evaporated.
3. Fresh water lake: most of the lakes in the world are fresh water lakes fed
by river and without flowing streams

Fish culture in natural water body:
Cage culture:
 Here the fish to be culture are held in a selection of water of following
river by being imprisoned in a cage of metal or bamboo structure,
supporting wire, nylon- bamboo mesh mates.
 Phewa, begnas and rupa lakes comprise about 800 hectors. Cage fish
culture has been started in the above three lakes through private
fisherman and government efforts.
Advantage of cage culture:
 Required less investment but high return
 Its installation is easy
 In emergencies it can be removed from one place to another
 Less chance of being attack by predators
 The number of fish required at a particular time can be harvested and in
this way it helps t maintain the non seasonal supply of the fish.
Disadvantage of cage culture:
 During feeding a good amount of food passes out through the mesh,
hence enough loss of food.
 The cage fish are unable to get the natural food of their choice.

 In certain season, especially summer the oxygen concentrated decreased
so, more chance to mortality (death rate).
Construction and design of cages:
1. Bamboo cage:
 Cages are made of split bamboo mat supporting on frames
measuring 10m3 size (2*2*2.5m3) and 8m3 (2*2*2m3) size.
 During tests of such cage with coal tar painting are being planned
 The bamboo could last for 2 year as a float as well as for framing
material using knotless polyethylene net.
2. Iron angle and netlon plastic cage:
 Iron angles of 13mm or 19mm were welded together to formation
frame of 4*4*2.5 m3 and net –lon plastic mesh of 10mm or 5m
was fixed with the nylon twines in the angle iron frame
 Four 200 liter empty oil drums were mounted in welded frames to
float the cage at a depth of 2 meter
 The cages were provided with a top cover of chicken wire mesh or
old nets

 The durability of such cages has been estimated to be about 10
years with minor repair and maintenance.
3. Japanese vinylon net cages:
 These cages came in 73.5m3 (7*7*1.5m3) 50m3 (5*5*2m3) and
13 m3 (*3*3*1.5m3) sizes
 The mesh bar ranged from 7 mm to 30mm
 They were mounted on rectangular bamboo frames which also
serve as floats

Species use in cage culture:
In Nepal mainly two species of carp are popular
1. Silver carp ( phytoplankton)
2. Bighead carp (zooplankton)
For cage culture fish should be need following characters:
 Natural ability to grow fast
 Ability to adopt to crowed condition
 Easy handling and harvest
Management of cage fish culture:
1. Maintenance of cage:
 it is essential to keep the cages clean to reduce mortality, sponges,
algae are common fouling agents in fresh water.
 Cages, nets and frames must be checked at interval for signs of
damage, and tear and repair or replaced or sun dried of necessary.
2. Growth check:
 Sample of fish should be taken at regular interval and weighed, so
that the growth of stock can be monitored.
 It help to recognized disease and feed conversion ratio
3. Feeding:
 Moist ball of feed or pelleted feed any be convenient feed on the fish
by placing them on the feeding tray.
4. Harvesting:
 Harvesting can be done by using large scoop net
 Fish in cage are harvested when, fish have reached a marketable size
 Further production is negligible
 Daily production will be improved by replacing the old with a new
fingerlings

The cages are harvested in two ways:
1. Partial harvest
2. Total harvest
1. Partial harvest:
 In partial harvest only a certain number of selected fish are removed. I,e,
largest or unhealthy individuals
 Their removal reduce competition for food and space their by allowing
small fish to reach marketable size faster
2. Total harvest:
 A complete harvest is advised when over production is planned to
improve by replacing old stock with new fingerlings.
Pen culture:
 Also known as encloser culture
 It is defined as raising of fish in a volume of water enclosed on all
side except bottom, permitting the free circulation of water
 Started from 1984 at lakes of pokhara valley
 This system can be considered a hybrid between pond and cage
culture

Advantage:
 Economic use of natural water resources
 Removal of organic matter and nutrient accumulated in plankton as fish
flesh
 Low investment and high return
 Providing employment to landless
Disadvantage:
 Possibility of losing the whole stock due to inclement weather such as
flood and typhoons
 High cost of labor and construction
 Unable to construct a pen when bottom is rocky or rough
Suitable species for pen culture:
 In Nepal silver carp, bighead carp, and grass carp are popular for culture
in pens
 Using common carp is risky for pen culture because of its bottom feeding
habits.
Construction and design of pen:
 Pen size is directly related to the rate of water exchange and the cost per
unit area.
 Small size pens usually allow for higher fish yields, lower production
cost and easier management.
1. Wall net:
 Wall net is the main body of pen

 Nets used in pens are made of 10 mm polythene thread with mesh
size of 2-2.5 cm
 Height of net above the maximum water level of the lake should
be about 90-120cm
2. Bamboo or wooden stakes:
 Used to support the wall net
 Bamboo poles of 8-9 cm in diameter or wooden poles of 3*4 are
driven into the mud to a depth of 30-60cm
There are several types:
 Main stakes: for hanging well net
 Pair stakes: are set up on each side of the net at every other main stake
are set up on each side of the main stake to keep stone sinker from
moving
 Supporting stakes: used to support main stake
 Protecting stakes: it prevent oats or debris form hitting the net
3. Concrete block and rod chamber:
 Concrete block of 3-5 kg weight are to be put into the bottom line
of the wallnet to prevent fish escaping near the bottom
 Sometimes u shape iron anchor are placed into 20 cm depth of silt
with a distance of 0.5 m for reinforcing (supporting) to the pen.
Care and management of pen culture:
 Regular monitoring , cleaning and repairing of wall net and poles
 Regular growth check of fish at least once a the month
 Regular water quality monitoring
 Monitoring of feeding behavior
Harvesting:
 Pen is un-drainable, so the most common means of harvesting fish in en
is by seining.

 Seining generally start at the deeper end of the pen and end of the shallow
end
Classification of fish farming system:
1. On the basis of level of intensity
 Extensive (1-5 ha)
 Semi intensive (0,2-0.3ha)
 Intensive (fully facillated)
2. On the basis of fish species:
 Monoculture
 Poly culture
3. On the basis of enclose:
 Cage
 Pond
 Pen
 Race- way
4. On the basis of integration:
 Rice- fish farming
 Horticulture fish farming
 Livestock fish farming
Preservation and management of fish and fisheries:
 Normally the fish farms are located far off from the market place and
there is chance of fish decomposition and the uncertainties of their sale
in market, therefore becoming a very important part of commercial
fisheries.
 Freshness of fish: freshness is usually judged in the trade entirely by
appearance odour and texture of the raw fish.
The most important things to look for the freshness of fish are:
 The general appearance of the fish including that of the eyes, gills,
surface slime and scales and the sources of the flesh.

 The odour of the gills and belly cavity
Method of preservation: preservation can be done both for short and long
duration:
1. Preservation for short duration:
 Chilling (low temperature): this is obtained by covering the fish
with layers of ice. However, ice alone is not effective for long
preservation, because melting water brings about a sort of leaching
of valuable flesh content which are responsible for the flavor.
2. Preservation for long time: when the preservation is required for long
period of time, the fishes are passed through the cleaning , gutting and
conservation and storage.
 Cleaning: during cleaning, first washed thoroughly in cold, clean
water to remove bacteria, blood, feces, and mud etc.. from the body
surface of the fish.
 Gutting: after cleaning, the fishes are cut along their mid ventral
side and their visceral organs are removed. By removing viscera,
the bacteria in the gastro intestinal tract and enzymes of visceral
organs are removed along with it to prevent bacterial
decomposition.
 Conservation and storage: conservation is necessary to keep the
dead fish in fresh condition, for a quite a long time. This is achived
by employing any one of the methods of like freezing, drying,
salting, smoking.
Freezing:
 Freezing means removal of heat from the body. To check the
enzyme, bacteria action it is preferred to store the fish under lower
temperature (below 6 degree C)
 Ice is put inside the body cavity in large fishes. The fishes are
arranged boxes and stocked

Drying:
 Drying involves dehydration I.e. the removal of moisture contents
of fish
 When moisture contents reduce up to 10 %, the fishes are not
spoiled provided they are stored in dry conditions.
 Fish drying is achieved either naturally or by artificial means.
Natural drying: in natural drying the fishes after being caught are
washed and dried in the sunshine.
Artificial drying: in artificial drying the killed fishes are cleaned, gutted
and have their heads removed. They are then cut lengthwise to remove
large parts of their spinal column, followed by washing and drying them
mechanically.
Salting: salting is a process where the common salt (sodium chloides) is used
as a preservative which penetrates the tissue, thus check the bacterial growth
and inactivate the enzymes. During the process the small fishes are directly
salted without being cleaned. In the medium and large size fish the head and
visceral are removed and longitudinal cuts are made with the help of knives in
the fleshy area of the body. Then the fish is washed and filled with salt for
uniform penetration through flesh.
Dry salting: in this process the fish is first rubbed in salt and packed in layer
in the tubs and cemented tanks. The salt is applied in between the layers of
fishes in the proportion of 1:3 to 1:8 salt to fish.

At the end of 10-24 hours the fish are removed from the tubes and washed in
salt solution and dried in the sun for 2 or 3 days. Large fish los about one third
and small fish about one half of their dressed weight.
Wet salting: the cleaned fish are put in the previously prepared salt solution.
It is stirred daily till it is properly picked.
Smoking: in this method, fish is cleaned. It is then exposed to cold or hot
smoke treatment. In cold smoking, first a temperature of 38 degree Celsius is
raised from a smokeless fire. After this heating cold smoke at a temperature
below 28 degree is allowed to circulate towards the fish. In case of hot
smoking, first a strong fire produces a temperature around 130 degree Celsius.
This is followed by smoking at a temperature of 40 degree Celsius.

Unit-3 Aquaculture
Pond fish culture
 it is the most common method of fish culture
 in this case water mass is maintained by artificial erected dike where fish
are grown
 pond are usually filled by rainfall, canal or spring water
 they differ widely in shape, size, topography, water and soil qualities
Fish pond can be classified into different types based on water source, site and
method of construction, drainage type, construction material and water
movement etc..
Types of pond:
Based on water source:
1. Ground or spring water ponds: they are supplied from a ground or spring
water either in the pond or very close to it. Water can be supplied by
pumping or using other methods.
2. Rain fed ponds: they are supplied from rainfall and surface runoff. Water
supply is very low during the dry season. Water quality differs based on
season
3. River/lake/ reservoir: they are supplied from the water body such as
river, stream, lake, reservoir or an irrigation canal.
Based on site and method of construction:
1. Sunken pond: sunken pond floor is generally below the level of the
surrounding land. The pond is fed by groundwater, rainfall or surface
runoff. They are generally undrainable or partially drainable.
2. Diversion pond: these are constructed by bringing water from another
source to the pond. Since natural gravity is used to fill the pond, no pump
is needed. 3 types of diversion pond: embankment pond, excavated pond
and contour ponds

Based on constructing material:
Earthen pond and cement pond
S.N. Earthen pond/ temporary type Cement pond/ permanent type
1 Require low cost for construction Require high cost for construction
2. No high technical knowledge High technical knowledge
3. Natural environment for fish can be
created
Difficult to create natural
environment for fish
4 High amount of water loss Low amount of water loss
5 High risk of predator Low risk of predator
6 Turbidity of water Is high Turbidity of water is low

Earthen fish pond
Earthen ponds are made up by clay soil. It is popularly used in Nepal because
it is cheap and easy to construct.
Advantages:-
 It can be easily constructed with relatively lower degree of engineering
 Provision of ample natural food generated with less effort.
 More chances of entry of flood during heavy rain.
Disadvantages:-
 Problem of regular soil erosion
 Higher chances of entry of weed fish and unwanted aquatic weeds
Cemented fish pond:-
Pond that is constructed by using cement concrete is called cemented pond. It
is generally constructed in research station. It requires higher installation cost
so farmers cannot afford this pond.
Advantages:-
 Though initial investment is higher to install cemented pond but over all
maintenance cost their after are relatively lower than the earthen pond.
 water turbidity can be effectively regulated
Disadvantages:-
 Higher initial cost for installation
 Problem of higher water temperature in summer
Plastic or fiber glass pond: they are entirely constructed from plastic or
fiberglass.
Pond design and construction
Site selection for pond construction:
Selection of site is very important because:
 The success or failure of fish farm depends on the site selection
 The productivity and utility of pond depends on the site selection
 The construction cost of fish farm depends on the site selection

 Once the pond is constructed in wrong place, it is difficult to correct it
Before constructing a new pond the following factor must be considered:
 Is there an adequate supply of water for a pond
 Is the soil able to hold water for a fishpond
 Is the land a good shape for a fishpond
 Is there a market place nearby
 Are there roads and vehicle from the pond area to a market place
Land area and topography:
 The projected land for fish pond construction should be relatively level.
Steeply sloped land is not suitable for building ponds. A slope is about 1
% is ideal
 The selected area should not be subject to pollution in run off from
adjacent land
 If possible, the land must be slightly lower than the water source, so that
the pond can be filled by gravity rather than by pumping.
Water supply:
 The most common source of water used for aquaculture are surface
water (river, lakes) and ground water (wells, )
 A good water source will be relatively free of silt, aquatic insects,
predators, and toxic substances and it will have high concentration of
dissolved oxygen.
 For earthen pond the water 100/ lit per minute for each hector of ponds
that will be built
 If the selected sites has relatively poor soils 2-3 m3 per minute per
hector

Soil:
 Land should be comprised of good quality soil with little or no gravel or
rocks either on the surface of mixed in farmers should consider importing
clay soil for compacting in the fish bottom, sides and core trench to
minimize seepage.
 Soil that will be used to build the dykes must contain at least 20 % clay
so the finished pond will hold water throughout the growing period.
 Take a handful of soil and wet it, so that it begins to stick together
without sticking to your hand. Squeeze it hard, then open your hand
 If the soil retains the shape of your hand, there is probably enough clay
in it to build a pond
 If the soil does not retain the shape of your hand there is too much sand
in it.
 Take a handful of moist soil and squeeze it into a ball
 Throw the ball into the air 50 cm and then catch it
 If the ball fall apart, it is poor soil with too much of sand. If the ball sticks
together, it I good soil with enough clay in it.
Pond shape and size:
 It may be square or rectangular shape
 There is no hard and fast rule regarding the size of the pond, however
nursery pond should be small and shallow
 For nursery pond, 100-200m2 area and 1-1.5 m depth is suitable
 For rearing pond 200-500 m2 area and 1-105 m depth is suitable
 Breeding pond 5-10m2 area and 0.8 -1 m depth
 It is recommended that pond have a gentle slope of about 2:1 . this
however depends on the size of the pond
 Use soil excavated from the pond area to construct the dykes

Pond design and construction:
 Layout of ponds: it is very important to considered the layout of the
pond in relation to the topography of the land, source of water and
drainage. Also important is to allow for expansion of the fish farm in
future. The ponds, drainage canal and other facilities should be laid out
in such a way that additional ponds can be constructed in future.
 Pond shape and size: square and rectangle shaped pond are easy to
build. Rectangular pond are more practical to construct, feed and
manage. However the pond can have a different shape based on the land
available for pond construction. There is no ideal pond size for growing
fish and they vary from 200 m2 to 1 ha. From the management point of
view, an area of 300-1000 m2 is good size for a family pond.
 Depth: the water depth is usually 30 cm at the shallow end and 1.0-1.5
m at the deep end. The pond should be deeper if there is no provision of
water supply from outside so it can hold at least 1.0 m water in the dry
season
 Orientation : wind play a role in pond design. Strong wind generated
waves and the waves will erode the side of the dikes. To minimize the
dike damage, the longer pond dimension should be positioned parallel to
the direction of the main prevailing wind direction so that the wave
action be on shorter length of dikes and erosion would be less
 Dykes: The most important component of a pond Is its wall (also referred
to as the dykes: leaves or embankments). The pond leaves should be well
compacted and have a gentle slope
Inlet, outlet and overflow: in improved fish culture, regular water supply,
draining out and overflow are necessary. Therefore, inlet, outlet and overflow
popes are required. It is better to position inlet and out let diagonally. If a pipe
is used as an inlet, it should be projected enough into the pond so that water
will fall into the pond at 90 degree directly into the pond and prevent dike
erosion by falling along the dike. The inlet and overflow pipes should be at
least 20 cm above the water surface to prevent fish from escaping. Outlet
should be placed at a level below the lowest level of pond bottom.

Guidelines for pond construction:
 Clear all vegetation, rocks, wood etc.. from the construction area
 Remove the top soil of 15-20 cm and keep it aside
 Inside the pond, dig a small draining ditch
 Form the inside slopes of the banks
 From the outside slopes of the banks
 Use the soil to build the banks, layer by layer and tightly packed
Fish feed:
The objective of feeding fish is to provide the nutritional requirement for
good health, optimum growth. Nutrients within the feed should also be
easily accessible to fish and be digestible. The growth of fish in pond is
directly related to the amount of food available in the pond. Natural pond
food is usually the most economical source of nutrient but these foods only
are not sufficient to produce maximum fish growth.thus proper management
of feeding is important to maximize yield.
1. Natural feed:
Occurs naturally in fish ponds and are considered as best food for fish. This
includes plankton, detritus (living algae/ aquatic plants), worms, bacteria,
insects, snails, aquatic plants and fish.
Plankton: plankton are an essential food for all fishes. And are especially
important as food for the adults of silver carp, bighead carp, catla and
tilapia. Plankton consist of two ecological group: Zooplankton and
phytoplankton
Phytoplankton includes cyanophyta, chlorophyta, pyrophyta and
zooplankton includes protozoa, rotifer, copepod and insect larvae.
Aquatic animals: others aquatic animal commonly used as fish food are
snails, clams, insects, aquatic worms etc.. aquatic animals feed are
nutritionally complete rich in protein and are considered to be the best
natural food for omnivorous and carnivorous fishes.

Detritus: living/ aquatic plant of the pond. If not fed upon by animals, die
and slowly settle down to the bottom of the pond. These non living
particulate organism matters covered by microorganism is called detritus.
Aquatic and terrestrial plants: are not only used as green manure and
compost, but are also ingested directly by herbivorous fishes. There are
many aquatic plants which are directly serves as fish feeds including hydra,
pistia,. Terrestrial plant used for nepier, mulberry, banana, ipil ipil, pea and
beans leaves, etc.. the nutritional value of both aquatic and terrestrial plants
for fish depends on the palatability and digestibility of the plant as well as
its nutritional composition.
2. Supplemented feed: usually consist of feed materials available locally
such as terrestrial plants or agricultural by products
 Many kinds of feed materials may be used as supplementary feeds
for your fish such as:
 Grass, leaves and seeds of leguminous shrubs and tree , vegetables
 Small terrestrial animals : earthworm, snails
 Rice: broken bran, hulls
 Wheat bran, flour
 Oil cake after extraction of oil from seeds of mustard, coconut ,
groundnut cotton , sunflower, soybean.
 Slaughterhouse waste: blood, rumen contents
 Manure: chicken drooping, pig manure
Supplementary feed are available in two forms:
1. Dry feed stuff: such as cereal and cakes with about 10 % moisture. These
are easier to transport, store and to distribute
2. Wet feedstuff: such as blood, rumen content, molasses and brewery
waste with 30-60% moisture. Moist feed do not keep well and only small
quantities should be prepared at a time.

Complete feed:
 Are made from a mixture of carefully selected ingredients to provide all
the nutrient necessary for the fish
 They are made in a form which the fish easy to eat and digest
 These feed are difficult to make on the farm and are usually expensive
to buy
 The feed must be complete in terms of nutrients supply
Feeding frequency: the feeding frequency is the number of times fish in a pond
fed in a day
For optimum growth and feed conversion each feeding should be about 1%
body weight. In grow out ponds feeding 2 or 3 times a day is adequate.

Types of fish culture:
Monoculture:
 Only one fish species is reared in water body.
 Typical fish reared in this way are trout, tilapia, catfish etc..
 Supplementary feeding is compulsory to ensure production
 Only controlled, high input system will give better result with
monoculture
Advantage:
 Easy to feeding
 Easy to operate
 Suitable for farmer having limited land resources
 Selective harvest of marketable fish can be employed
Disadvantage:
 Natural productivity of the pond is not fully utilized
 Available space in the water column is not utilized
 More chance of epizootic disease and parasite
 More risk of water quality problems like dissolve oxygen depletion
Polyculture:
 Two or more fish species with different habitats and different food
preference, are stocked together in such densities that there will be
almost no food or space competition
 Poly culture give higher yield than monoculture under the same
condition.
Advantage:
 Full utilization of feeding
 Full utilization of space available in the water column

 Full utilization of compatibility of species
 Full utilization of formulated feed
 Less chance to fail the enterprises
 Less chance of epizootic disease and parasite
 Polyculture play and ecological role in maintaining water quality, thus
creating a more conductive environment for the fish.
Disadvantage:
 Difficult to harvest
 Difficult to maintain the food for all species of fish
 Need of high technical knowledge
 Transmission of disease
Raceway culture:
 Rising of fish in running water
 Raceway ponds are basically two types:
1. Linear type with pond arranged in sequence
2. Lateral types with pond layout in parallel

Raceway culture of rainbow trout in cold water is one of the recent and
established fish culture practice in Nepal.
Rainbow trout fish farming technology and practice:
 Clean and cold water is essential for trout culture
 Trout culture site must have perennial water supply with a temperature
ranging from 10-200 but optimum temperature for best growth is 15-18
degree C.
 The water should be clear and rich in dissolved oxygen
 It is better to construct the raceway ponds rectangular with sufficient
slope
 The area of 50-150m2 with water depth 60-90 cm Is suitable.
 Trout need to supply high protein in content feed In pellet form
 Generally 35-40% crude protein is necessary
 Reach marketable size 200-300 gm within 12-24 month
Integrated fish culture:
1. Horticulture fish farming:
 Fish culture can be done along with the fruits, vegetables and
flowers.
 These horticulture products would not only provided the additional
income to the fish farmers but also improves the environment.
 In one hector pond area 0.3 hectare land is available in shape of
dikes on which any banana, papaya, plants having low root system
can be cultivated.
 Flowers and vegetables can be grown also in remaining space.
 Leaves of fruits and vegetables can be used as a feed for fish while
pond water can be used for irrigation and pond bottom soil can be
used as a good fertilizer for the plantation.

2. Livestock fish farming:
 The highest production obtained so far in integrated fish farming
are with pigs, ducks and poultry a popular technique in Asian
 In some country fish farming also integrated geese, rabbits, sheep,
and cattle buffalo with fish culture on a small scale.
 The main fish species stocked in animal fish system either in mono
or poly culture are the common carp, nile tilapia.
3. Pig fish farming:
 The integration of pig with fish farming is highly profitable.
 The digestion of pig is incomplete and about 30% of the undigested
feed is excreted in feces which serves as direct food for fishes.
 In this system supplementary fertilization and feeding are not
required for fish culture.
 Pigs are reared in pens or sites built on the banks of the fishpond
(wastes are washed out) or construction over the pond on piles or
wooden stilts and have a lattice type of floor that allow waste to
fall directly into the pond

4. Duck fish farming:
 The duck fish farming system not only result in more economic
benefit to the farmer but also the fish and ducks are benefited by
their co- existence.
 The drooping of the duck acts as substitute fish feed and pond
fertilizers which account for 60% of the total input cost in fish
culture.
 The duck feed on such organism from the pond such as larvae of
the aquatic insects, tadpoles, aquatic weeds. That do not form the
food of the fish.
 Ducks are reared in shed built on the bank of the ponds or
constructed over the pond on stilts, or sometimes built on floating
platforms.
 Generally a small section of the pond is enclosed by wire netting
and connects with duck shelters
 A shed of 20 m2 is capable of accommodating about 300-400
ducks.
 In duck fish farming it is advisable to release fish fingerlings of
more than 10 cm size, otherwise the ducks may feed upon the
fingerlings.
 As duck manure enhance plankton production, the plankton
feeding fish such as silver carp, bighead carp or catla along with
common carp are ideal for duck fish farming.

5. Poultry fish farming:
 the integrated farming of poultry and fish is a compatible business
since fish and poultry are mutually complementary.
 The former provides fish meal, a protein rich poultry feed and the
later its drooling which acts as fertilizer for fish pond.
 the integrated farming of poultry and fish is only practiced In a few
countries in Asia (Philippines, china, Indonesia) and is on
experimental scale in Africa, USA.
 poultry are reared in pens beside or over the ponds, in the
traditional way, in roughly the same condition as duck, generally
at a density of 1000 to 6000 birds per hectare.
Fish culture in paddy field:
Rice fish farming:
 It is an integrated farming practices in which fishes is cultured in
rice field.
 Rice is taken as primary crop and fish as secondary crop
 In Nepal it introduced in 1964 by department of fisheries at present
it covers about 218 ha
Suitable species for rice fish culture:
Fish species cultivated in rice field having following characteristics
 They must thrive in shallow water
 Must tolerate high water temperature
 Must withstand fairly high turbidity
 Must tolerate low dissolved oxygen
In Nepal two species are popular for culture in rice field common carp
and tilapia:

Rice variety
Mansuli: late maturity (155 days)
Sabitri: moderate maturity (140 days)
Radha : early maturity (125 days)
Technique of fish culture in rice fields:
1. Site selection:
 Availability of adequate supply of water
 Soil having good water holding capacity with ph 7 -9
 Rice field should be near to residence for proper care and
management
 Site which is subject to flood and landslide should be avoided for
fish culture
2. Dike / bund construction:
 The dike should be suffuuently increased so that it can hold at least
15 cm of water
 Generally a dike 50 cm wide at the base , 60 cm height with 30 cm
top width is construct around the rice field

3. Trench construction:
 The trench serves as a refuge for fish when the water level drops
to low, when the temperature of rice field is too high and when
there is threat of predator
 It also serves as catch basins during harvest
 Several types of trench are in practices: peripheral liner, t shaded
trench etc.. in Nepal peripheral trench is popular
 In this system a trench of 50 cm wide and 50 cm deep are
constructing all around the dikes.
4. Size of rice plot: rice fish plot should be 200-2000 m2
5. Inlet and outlet construction: inlet and outlet are placed diagonally
opposite so that there is more circulation of water in the rice field. Inlet
and outlet are provided with screens to prevent the entry of unwanted
fish, tadpoles
6. Fish stocking: small fingerlings can be stocked soon after rice is
transplanted while larger fingerlings should not be stocked until rice has
turned fully green . 6000 fingerlings/ ha of common carp or 9000
fingerlings /ha of tilapia prevent escape of stocked fish
7. Fish feed: rice bran and mustard oil cake 1:1 @2-4% body weight of fish
per day is provided.
8. Care and management: snake control: using snake trap, bird control,
prevent water leakage, do not use pesticide as far as possible
9. Harvesting: fish should be harvest before a week of rice harvest. For
harvesting the fish the water of rice field should be drained gradually and
fish are harvested from the trench.
Cultural practices and management of pond fish culture:
Pre socking management
A)Pond preparation:
 Pond preparation is necessary prior to stocking to create a
favorable environment for fish growth.

 Pond should be drained and dried, if possible until the pond bottom
crack.
 A dry pond enables the farmer to remove excessive bottom mud
and weeds, level the pond bottom, and repair the dykes.
 The vegetation around the pond should be cleaned
 Grass should not to be completely removed, however it helps to
hold soil on the dykes and reduce erosion
 The screen on inlet and outlet pipes should be repaired.
b) Pest elimination:
 If pond cannot be dried out completely, they should be treated a week
prior to stocking to eliminate any predatory fishes or other pests.
 Common pond treatment are lime, tea seed cake or rotenone
Liming: lime kills all microorganism and fish predators as well as
corrects acidity in the pond soil so as to create a favorable environment
for fish. Lime is usually applied once only at the beginning of each pond
cycle. After that, the need for lining and the quantity of lime used will
depend on the soil and water characteristics.
Tea seed cake: this is a residue of the fruit of plant (camellia sasanqua)
after the fruit oil is excreted. The byproduct contain saponin, which is a
poison to fish. At a concentration of 10 mg/l , saponin cause fish to die
in a few hours. Tea seed cake in powder form is first soaked in water
until dissolved and this water is then evenly spread into the pond.
Rotenone: this is excreted from the roots of a plant (Derris uliginosa) .
The excreted solution contain about 25% rotenone, which is a poison to
fish. The rotenone solution is first diluted 10-15 times with water and
then evenly spread into the pond.
c) Water filling and initial fertilization:
 After liming, the pond is filled to about 1-1.5 m depth and initial
fertilization is done.

 The purpose of adding fertilizer to fish pond is to encourage growth of
natural food organism in the pond.
 More natural food enhance fish growth and less supplementary feed will
need to be added
 Fertilization provides phytoplankton with more nutrient which leads to
more phytoplankton growth.
 Zooplankton will fed on phytopnkton so will also flourish if fertilizer is
added.
 Most fish feed on both phytoplankton and zooplankton as well as any
supplementary feed added to the pond
d) Stocking and fingerlings:
 When sufficient natural food is present in the pond, the pond is ready for
fish stocking
 The green color of the pond water is an indication.
 Usually fingerlings about 4-6 weeks old and 2-5 g body weight are
good to stock the grow out pond where they will remain until harvesting
 Good quality fingerlings of similar age and size must stocked.
 Stocking density depends on fish species, types of management, pond
productivity and expected harvest size of fish.
 On receiving the shipment of fingerlings it should not delay in releasing
them into the pond.
 Most important the fingerlings should not be left in the sun to get too
warm.
 On arrival at the pond site, the fish should not be immediately released
into the pond because sudden change in water temperature or water
quality can harm the fish. Temperature should be 5 degree c or more in
temperature container and the pond water.
Post stocking management:
a) Feeds and management:
 Although carps and tilapia fish feed on natural food and so can
be grown without feeding, supplementary feeding in necessary
for better growth and more profit.

 Pangas catfish, African catfish, and rainbow trout culture are
solely depends on artificial feed.
b) Regular fertilization:
 Regular fertilization is necessary in ponds, especially for carps and
tilapia culture to maintain dissolved oxygen level and to encourage
growth of natural food organism in the pond.
 Fertilization is done in weekly or biweekly interval throughout the
culture period.
c) Daily management :
 In semi intensive carps and tilapia culture they generally do not
require large quantities of water to be flowed through the pond.
 However water must be available to replace water lost through
seepage and evaporation and also when necessary to flush out
any heavy phytoplankton bloom and maintaining water quality.
 The management of pond water quality is important. Water
temperature, dissolved oxygen, ph., amount of plankton and
nutrients levels must all be managed to provide best possible
environment for growth and general well-being of the fish.
 The condition of the pond and the behavior of fish should be
observed twice early morning and afternoon.
 Water color, plankton concentration, water smell, and fish
activities including surfacing behavior should be noted.
 If the fish gasp for air at the water surface in early morning and
continue to surface after sunrise, the dissolve oxygen content is
too low and fresh water should be added into the pond.
 Fish surfacing to eat food will swim forward, and this is a good
sign, where fish surfacing to gulp air tend to move slowly
backward as they are bad sign
 Other daily activities includes to observe water inlet and outlet,
growth of aquatic weeds, dyke erosion, dead fish floating,
predator attack etc..
d) Sampling:
 Sampling is a procedure where a representative number of
fishes from the ponds are caught by seining to get clear idea

about the growth rate of fish, their total biomass and health
condition
 Sampling of the fish should be done at least once a month
Importance of sampling:
 To know the growth rate of fish
 To determine the total biomass of stocked fish in the pond
 To examine fish health, diagnosis disease and take necessary
action
 To know if fish reach harvestable size
e) Harvesting:
 Harvesting is catching fish from pond for family consumption
or for selling purpose.
 Fish can be harvesting stating from about 4-5 month after the
fingerlings have been stocked, provided water temperature
remains suitable and good quality supplementary feed is
provided.
 The exact time for harvesting is determine by factors like the
preferred market size for fish, and by opportunity to achieve
good volume of sales and good prices (Friday, holiday, festival
time).
 In Nepal the most practiced stocking time is March/ April and
harvesting time is October/ December for carps, catfish and
tilapia
There are 2 types of harvesting: partial harvest and complete harvest
A partial harvest can be done using a drag net or a cast net, but for a complete
harvest the pond is seined 3-4 times and then drained to get all the remaining
fish.
Fish should not be feed on the day of harvesting, to allow the fish to empty
their guts, this will improve the survival and condition of the fish during
handling. It is preferable to harvest early in the morning so that the pond water
is still cool. This will reduce the fish stress while they are being seined or
collected.

Fish predators and their control
Weed and predatory fishes:
Weed fish:
 Unwanted, uneconomic, small sized fish that occurs naturally or
accidentally introduced in ponds along with cultivated species are called
weed fishes
 Weed fishes are non-predatory
 These fishes have high fecundity and naturally breed in ponds
 The weed fishes may be predator or non-predators
 Weed fishes have relatively good fecundity, attain sexual maturity in
summer and breed even without rain prior to the monsoon.
 The common weed fishes of Nepal are: sidre or pothia, faketa, rasbora
etc..
Predatory fish:
 Are the fish that prey upon other fishes
 They are carnivorous in nature
 There are numerous predators which prey on smaller fish than larger
fishes
 The common predatory fish in Nepal are hile or bhoti, magur, kabai,
nata, bam etc..
Control measures:
The eradication or control of the weed and predatory fishes from the
cultivated pond is suggested to be an important measure of pond
management.
a) Neeting: it is the conventional method to control unwanted fishes
in the pond and not to sure method. However, repeated neeting by
fine meshed drag net ensures successful removal of the weed and
predatory fishes largely.
b) Hook and line: this is one of the most conventional method and
used for catching mostly the piscivorous dishes like wallago,
channa . It consist of fish hook which is baited and a line attached

to it. Nature of bait, bait size and the size of hook determines the
selectively of the catch.
c) Draining out and drying the pond: complete dewatering of the
followed by the drying of bottom mud at least for one week is
suggested as a success method in eradication of unwanted fishes.
This keep the pond in hygienic condition and kill all existing
fishes.
d) Poisoning: this is the most effective method of eradicating the
weed and predatory fishes form any sized water body but its use
has been kept restricted because of its high toxicity effect to the
aquatic and sub aquatic animals. It also effect plankton and other
organism. Therefore poisoning should be done with caution and
proper dose to avoid harmful effect to human beings, livestock and
surrounding environment.
The fish poisoning are organophosphate ( thiomenton, Dimethyl
dichlorovinyl phosphate) chlorinated hydrocarbon: ( endrin,
DDT, BHC )
Preventive measure:
 Keep screen/ filter in the inlet pipe
 Stock the fish before the breeding season of weed and predator fish
 Repair the damage portion of pond dike before rainy season
 Care should be taken to avoid mixing of weed and predators with
cultivated fish seed
Aquatic weed and their control:
Positive role of aquatic plant:
 Serve as food of herbivorous fish
 Form based on food chain
 As a source of oxygen in water
 Reduce the water velocity
 Aesthetic value beautiful flower

Negative role of aquatic plant:
 Absorb nutrient from pond
 Shading effect
 Off flavor
 Hamper netting
 Some aquatic plant release toxic substances
Classification of aquatic plant:
1. Floating water: azolla, salvinia
2. Emergent plant: root in bottom soil leaves and flower are above the water
( water lily, lotus)
3. Submerged plant: hydrilla, ceratophyllum
Control of aquatic fish:
Use of biological agent: grass crap control floating emergent and submerged
weed. Tilapia control filamentous algae
Use of chemical: spray paraquat @0.02 kg/ha for floating weed, cuso4 @0.25
PPM FOR ALGAE
Manual and mechanical method: removed weed by using water weed cutter,
weed harvester
Predatory aquatic insects:
Aquatic insects are found in all types of fishpond and are harmful to fish in
earlier stages such as eggs, hatchlings and fingerlings. These insects not only
directly prey upon the larval stages but also complete with food organism and
the damage has often been mentioned as one of the major constraints to the
aquatic production. Common aquatic insects found in fishpond are
hemipteran, megalopteran etc..

Techniques to develop natural feeds:
In semi intensive aquaculture it is necessary to develop natural food in pond.
Two major techniques for the development of natural food in aquaculture
ponds are pond liming and pond fertilization.
Pond liming:
Liming is a recommended practice in pond aquaculture, which has several
beneficial effect on the pond and health of fish. However application of lime
is not a type of fertilization but it is usually applied to ponds for collection of
soil acidity and other several purpose.
Advantage of liming in pond:
 In general, it enhance the pond productivity, improves sanitation
 Kills pond bacteria, fish parasite and their intermediate life cycle
 Improve pond soil quality by promoting mineralization
 Supplies calcium needed for plant growth and for bone and scale
formation in fish
Use of lime should however be done with caution. Excessive of lime is
troublesome because of toxic effect.
Time of liming in pond:
Liming fishpond is not always necessary. In certain case, it may not only be a
waste of money but it can also be harmful to the fish. Lime is usually applied
only once, at the beginning of each culture cycle.
The following are the condition when liming is required:
 When water pH is to low (<6.5)
 When water alkaline is too low
 When organic matter content is too high
 When water get foul odor
 When there is threat of oxygen depletion
 When there Is a threat of outbreak of contagious disease or parasite

Liming materials:
Liming material used In pond are the same ones that are applied to agriculture
soil. Compound useful as liming materials contain either calcium or calcium
and magnesium.
Agricultural lime: calcite, caco3
Hydrated lime or slaked lime or builder’s lime: calcium hydroxide , ca
(OH)2
Quick lime or burnt lime: calcium oxide, CaO
Pond fertilization:
Pond fertilization is one of the key factor in increasing the productivity and
maximum carrying capacity of pond. In pond fertilization is aimed at
developing natural food and saving formulated feeds. Generally addition of
fertilization to the pond provides nutrient to encourage rapid growth of
phytoplankton which are the primary producer in the ponds.
Types of fertilizer:
A)Organic fertilizer
B) Inorganic fertilizer
Organic fertilizer: are composite in nature and contain all the natural elements
required for the metabolic cycle. These fertilizer contain a mixture of organic
matter and mineral nutrients, they are produced locally for example as wastes
from farm animals or as agricultural wastes.
Organic fertilizer may be of followings type:
 Livestock manure
 Compost
 Green manure
Advantage:
 They are relatively inexpensive

 Improve the pond soil structure, fertility and water holding capacity
 Readily available on farm
 It encourage bacterial growth which in turn favors better production of
the zooplankton
Disadvantage:
 It is difficult to transport
 Low contents of primary nutrients
 It is time consuming to collect and apply bulk materials to ponds on a
routine basis
 It is unsuitable for intensive high yield culture system
 The decomposing organic manure creates unhealthy conditions in the
pond favoring incidence of some disease as the gill rot.
Inorganic fertilizer: are chemical fertilizer that dissolves in the pond water
and provide their nutrients immediately. These fertilizer contain only mineral
nutrient and no organic matter, they are manufactured by industries to be used
in agriculture for improving crop production.
The different inorganic fertilizer used in fish ponds are as:
1) Nitrogenous fertilizer
 Urea, ammonium sulfate
2) Phosphorous fertilizer: single super phosphate , triple super phosphate
3) Compound fertilizer: Diammonium phosphate (DAP)
Advantage:
 Exact composition of nutrient available
 Mineralization is very fast giving quick effect on pond
productivity
 Easy to transport
 Lack of pollution
 No effect on pond depth

Disadvantage:
 Costly, not easily available
 Slow growth zooplankton
 Effective for short period
 May create water quality problem
Time of fertilization in new fish pond:
 If the pond is new, and good bottom mud has not yet formed
 Periodic basis (one or two week interval)
 When the pond water is more transparent (secchi disk visibility >40 cm)
 The secchi disk transparency can be used as a simple method for judging
plankton turbidity and the need for additional fertilization of a fish pond.
Turbidity: it refers to the decreased ability of water to transmit light cause by
suspended particle matter in the water. Transparency is measured using secchi
disk, nephelometer
Cause of turbidity:
 Planktons (zooplankton and phytoplankton): it is called plankton
turbidity. This type turbidity is generally desirable in fishpond
 Suspended particle of silts and clay: it is called clay turbidity
Effect of turbidity:
 Reduce light problem.
 Turbidity direct effect on fish which cause interfere gill function that
cause respiration problems
 Effect on vision of fish

Unit: 4 2022/7/21
Fish breeding:
Role of fish seed in aquaculture:
Like other farming system, fish farming being with the stocking of fish seed.
Timely and sufficient supply of good quality seed is essential for successful
fish farming. The demand of fish is increasing due to expansion of aquaculture
and enhance fishery in the country. Natural fish population have decline
during the last several years because of environmental degradation and over
fishing. Very few fish species can reach sexual maturity and spawn in stagnant
pond, when condition are appropriate. Hormone induced spawning is the only
reliable method to induce reproduction in these fishes. Hormones induces
spawning of fish has been used for almost several decades in Nepal.
Production of genetically pure, healthy, uniform size and same aged seed is a
major objective for fish seed producers. There are many issues related to fish
breeding and quality seed production in Nepal. Some issues are genetically
degraded brood stock due to inbreeding, uncontrolled cross breeding, poor
brood stock management. This result reduction in reproduction performance,
slow growth rate and poor survival of fish and increase incidence of disease
and morphological deformities.
Hatchling:
 The larvae emerging from the fertilized egg after hatchling
 It is characterized by the presence of yolk sac hanging below from where
it draw its nutrition for 2-3 days.
 At this stage the mouth is not formed and hence it does not take food
from outside

Spawn:
 As soon as the yolk sac of the hatchling is absorbed it is known as spawn
 At this stage the mouth is formed and it starts taking small zooplankton
like rotifers and supplementary feed like egg yolk, finely powdered oil
cake, rice bran etc..
Fry:
 As soon as the spawn assume the shape of the fish and grow to about 1-
2 cm it is known as fry
 At this stage they are primarily smaller size zooplankton feeder
 It takes about 7-10 days for the spawn to grow up to fry stage
Fingerlings:
 As soon as the fry grow up to 10-15 cm size or roughly equal the size of
a finger it Is known as fingerlings
 Fingerlings is the proper size for stocking in table fish production ponds
 It takes about 30-60 days for the fry to grow up to fingerlings size

Brood fish management:
Brood fish means the sexually matured male and female fish which are able to
reproduce.
The characteristics of good brood fish are:
 Lively and active
 Free from parasite and disease
 Well-developed gonad
 Rapid growth, tolerance to poor water quality. Strong appetite
1. Selection of brood stock: generally 1-2 years fish weighing about 2-4
kg are used for breeding and they can be breed every year for several
years.
2. Sex determination:
Using sex organ:
The adult male fish has an elongated, backward projecting from of its
papilla. But in female fish the genital papilla has an oval form.
Sexual characteristics of male and female:
S.N. Character Male Female
1. Scales Rough with sandy
texture
Smooth and silky
2 Operculum Rough with sandy
tubercles
smooth
3 Pectoral fin Rough with sandy touch,
longer than female
Smooth and slippery,
smaller than male
4 Abdomen Round and firm and not
too soft to the touch
Soft and palpable

5 Vent Elongated, backward
projecting from of its
papilla
Genital papilla has an
oval form
6 Pressure on
abdomen
On pressure above the
vent on the abdomen,
milky white fluids run
throughout vent
On pressure, yellowish
discharge or a few ova
may come out through
the vent
3. Source of brood stock: river, lake or reservoirs and stocked in proper
brood fish pond
4. Segregation of brood stock:
 At least 3-4 month before the breeding season the brood stocked
are removed and stocked in segregation ponds
 It is desirable to segregate the male and female into separate ponds
to avoid unwanted spawning
 In secretion ponds the stocked Is maintained under uncrowded
condition and fed on protein rich natural and supplement feeds to
assist faster gonad development
5. Feeding: if the fish are left hungry or staring the vitellogenesis phase of
egg developed is affected. If the food is deficient in essential nutrient

particularly the amino acid, vitamin and minerals the egg development
is adversely affected ultimately leading to failure to ovulation.
Quality of good breeder:
 The female should have a well-rounded and soft abdomen.
 The individual brood fish should weight 1-2 kg
 They should be hardy nature with the ability to remain alive out of
the water for long period of time is of special value
Induced feed breeding/ hypophysation:
The artificial process by means of which the extract of the pituitary is
introduces inside the body of both the matured male and female fishes, then
after being excited, they lay egg in the pond water and subsequently
fertilization takes place and the process is called induced breeding of fish.
The process of breeding is also called as Hypophysation.
Need of induced breeding:
 Insufficient food availability by nature source
 Collect pure seeds
 Reduce hormonal release under capture condition
 In same season, a carp can be induced to breed more than once
 Transportation cost become very low as the carp can be breed in any
desired pond
Method of inducing:
 Synthetic pituitary hormone extract can be bought from market: ovaprim
and ovatide
 Pituitary gland extract can be made by excising the gland from the
mature brooder

Inducing agent:
The main inducing agent commonly used for the artificial propagation
are:
 Extract of pituitary gland (PG)
 Human chorionic gonadotropin (HCG)
 Luteinizing releasing hormones analogues (LRH-A)
 And various gonadotropin hormones with different trade names
(ovaprim, ovulin, spawn pro etc..)
Extract of pituitary gland (PG):
 Pituitary gland extract is important for stimulating maturation and
ovulation of fish.
 The pituitary gland secrete two gonadotropin , the follicle stimulating
hormones (FSH) and luteinizing hormone (LH)
 The FSH cause the growth and maturation of ovarian follicle in female
and spermatogenesis in the testes of male
 LH helps in transforming the ovarian follicles into corpora lutea in
female and promoting the production of testosterone in males

Human chorionic gonadotropin (HCG):
 Pure gonadotropin hormone excreted from the urine of pregnant women
and contain LH and FSH.
 It can be purchased as freeze-dried powder sealed in glass ampoules
 It stimulate egg release from female fish
 The dose rate is 400-1000 I.U. of HCG to 1 kg of female and 150-400
I.U. of HCG to 1 kg of male fish
Luteinizing releasing hormones analogues (LRH-A):
 This synthetic hormone made up from different amino acid chains.
 This hormone acts as on the hypothalamus pituitary interface to raise the
level of gonadotropin secretion.
 It can be purchase as freeze dried powder sealed in glass ampoules.
Breeding season of cultivated fishes of Nepal:
Fish spices Breeding season
Common carp March-april, sep- oct
Silver carp May-july
Bighead carp May- july
Grass carp April- May
Rohu June- August
Mirgal June- August
Trout November-December

Dosage of pituitary extract:
 Female given 2 dose: initial dose: 2-3 mg/kg bwt and resolving dose/
final dose : 6-8 mg/kg bwt
 Male given only 1 dose
 For female of Indian major carps one initial and after 5-6 hour final dose
given
Injection frequency:
The total dosage is injected in either a single or a double dose. Many
experience have shown that double injection lead to a more predictable
spawning and a higher rate of egg laying. The male fish received only one
injection where female received their second injection.

Injection time:
The time of injection is adjusting to water temperature. Generally the spawning
of fish is done around mid-night. When single injection is used, the injection
is applied in the late afternoon or at evening so that the spawning will take
place at next morning. When double injection is adopted the first injection is
given in the morning and the second given 8-12 hour later for Chinese carp and
6 hour later for indigenous carps.
Injection route:
Injection may be either intramuscular or intra peritoneal. The intramuscular
route is effective when the fluid to be injected does not 2-3 ml. for greater
volume, the intra-peritoneal route is more appropriate because the peritoneal
cavity has much more space in which to hold the injected fluid than muscular
tissue.

Spawning:
After injection to the brooders a set of brooders are released into the brooding
hapa. In hapa breeding, the hapa is the fine netting, rectangular in shape and is
held by 4 bamboo poles one at each corner. Closed meshed mosquito netting
is preferred for that purpose as its meshes will allow a good circulation of water
and will also not let the egg and milt escape through the meshes. The hapa
measures the range of 3m* 1.5m*1m for breeder weighing to 3 to 5 kg. The
height of hapa should remain about 20 cm above to the level of water. The roof
can be closed or open.
The spawning takes place within 3-6 hour following the 2nd
doses. It turn out
the mid night if the second injection was given in the evening, successfully
induced breeding result in the spawn of fertilized eggs. The fertilized egg are
transparent, pearl like whereas unfertilized egg are opaque or whitish.
Incubation and hatching:
It includes the process by which the fertilized eggs obtained from the brood
fish develops through smooth embryonic development to hatchling and
subsequent stages. The fertilized egg are generally collected after water
hardening and transferred to special incubating devices for hatching. Various
type of hatching devices or incubator are in practices, ranging from simple
hapa to zoug jars with temperature controlled water supplies but the
commonest one is Chinese type circular incubation tank.
Fecundity:
Fecundity refers to the number of eggs contained in the ovary prior to spawning
period. It can be categorized into two groups, absolute and relative fecundity.
Absolute fecundity: is the total number of egg in the ovary of an individual
fish.
Relative fecundity: is the number of ripe eggs per kilogram weight of female
fish.

Fecundity of cultivated fishes of Nepal:
Fish species Relative fecundity (eggs/kg body
weight)
Common carp 100000-200000
Silver carp 60000-80000
Bighead carp 50000-60000
Rohu 200000-400000
Grass carp 60000-80000
Tilapia 500-1000
Rainbow trout 2000-4000
Breeding of fish:
1. natural propagation
2. semi-natural propagation
3. artificial propagation.
. For natural propagation, males and females are placed together in a breeding
area such as a small pond or an enclosure where they spawn naturally. This
method is usually used, for example, to produce tilapias cheaply.
For semi-natural propagation, the fish (usually the females only) are first
given one injection of chemicals, such as a pituitary gland* extract, which will
trigger spawning. Males and females are then placed together in a specially
prepared breeding area such as a small grassy pond or an enclosure where
spawning takes place. The fertilized eggs are usually collected and reared under
improved conditions, either natural or artificial.
For artificial propagation, the females are given one or more injections of
chemicals which regulate the final ripening of dormant eggs in the ovaries. As
soon as the eggs are ripe, they are stripped from the females. The males are
usually also injected. Eggs are artificially fertilized with sperm obtained from
the males and reared under controlled conditions.

Each of these propagation methods is controlled by a series of environmental
factors, as shown in the chart below for common carp, for example.
NATURAL PROPAGATION
SEMI-NATURAL PROPAGATION

ARTIFICIALPROPAGATION
Selecting suitable breeders
When the breeding season comes, bloodstock should be carefully selected.
Only fish that are ready to spawn should be used. Select fish with the
following characteristics.

(a) Males should release a few drops of milt when the abdomen is slightly
pressed.
(b) Females should have a swollen and protruding genital opening,
reddish/rose in color, and a well-rounded and soft abdomen, showing that the
gonads are developed up to the dormant stage.
Using pituitary glands to propagate fish
If you wish to propagate your fish semi-artificially or artificially, you need a
supply of the chemicals (or hormones*) which play a decisive role in ovulation,
the final ripening of the dormant eggs. These chemicals, the gonadotropins*,
are produced, accumulated and stored in the pituitary gland of the fish, also
called hypophysis*, while they become sexually mature.
This small pituitary gland can be found in the upper part of the fish head, on
the ventral side of the brain. It is quite easy to collect such glands from mature
fish, store them for later use if necessary and extract the gonadotropin
hormones from them,

It is very important to collect pituitary glands from suitable fish, to be certain
that these glands contain enough gonadotropins to be effective. Select fish with
the following characteristics:
 sexually mature;
 preferably alive or freshly killed;
 suitable size.
The pituitary gland can be collected from a freshly killed fish in two ways:
by cutting open the head or by removing the pituitary gland with a drill. It is
easier to work on the head of a fish if you have a wooden frame to hold it firmly
in place when cutting or drilling.
Collecting pituitary glands by cutting open the head
To cut open the head, proceed as follows.
(a) Remove the top part of the skull
with a saw or a strong sharp knife.
(b) Locate the pituitary gland in the
brain mass.
(c) Remove it carefully with forceps.

Collecting pituitary glands by drilling into the head
It is often easier to use a drill, preferably an electric one, and a special drilling
head which you can have made in a local workshop. Proceed as follows.

(a)Select or make a drilling head
that is the correct size for you
(b) Locate the drilling point on the
top point of the skull, as shown.
(c) At the drilling point, press a
wooden guide piece (with a hole
drilled) against the skull.
(d) Drill through the top of the
skull, the brains and the base of
the skull, down to the mouth
cavity.

Unit: 5 2022/7/23
Live fish transportation:
Fish transportation is a process to transport fish of different life stages by
different means. It plays an important role in the distribution of quality fish
seed in different areas along with carrying brood fish from fishpond to
hatcheries and distribution of table fish for sale in distant markets. Thus the
purpose of fish transportation are for breeding, for stocking in ponds, and for
selling live fish.
Feed seed (fertilized egg, hatchlings, fry and fingerlings) come from hatcheries
and nurseries which are often located far away from the production pond in
which the fish are to be reared. The seed therefore need to be transported as
economically as possible in a healthy condition and without mortality. Unless
due to careless is taken during transportation, there may be complete mortality
of fish see which means a waste of money and time.
Stages of fish for transportation:
 Spawn or egg: egg of blastula stage or beyond morula stage are proper
for transportation.
 Hatchling or larvae: 5-10 mm (3-10 days)
 Fry stage: 1-5 cm (3-4 weeks)
 Fingerlings: 7-10 cm (4-10 weeks)
 Brood fish: more than 1 kg size
Factor affecting fish transportation:
Transportation of live fish from one place to another must be done carefully,
since a poorly organized effort may result in mass mortality during
transportation as well as after that. Thus, following factors that must be taken
into consideration are tolerance to transport, quality of fish, oxygen, ph.,

carbon dioxide, ammonia, water temperature, density and activities of
transport fish and stress in transport fish.
Tolerance of different fish species to the stress during transportation:
Fish species Tolerance level
Rohu Medium
Mirgal Low
Catla Medium
Common carp High
Bighead carp Medium
Tilapia High
Rainbow trout low
Cause of fish mortality in transportation:
The problem in transportation of fish seed arise form the fact that a large
number of fish is held in a small amount of water during a certain period.
Mortality of live fish at all stage during and immediately after transport may
be caused by:
 Oxygen starvation due to constant respiration and oxidation of excreta
 Increase the temperature of water of the container
 Accumulation of toxic wastes such as ammonia and carbon dioxide
 Decrease in Ph. due to increase of carbon dioxide and organic wastes
 Hyperactivity, stress and exhausted of the fish due to splashing in the
container wall.
Characteristics of fish for transport:
 Healthy and active: healthy fish are bright and fast movement
 Uniform in size
 Free from disease
 Not very small and weak. Treated against disease

Condition of fish before transportation:
 Spawn, fry and older fish for long transportation have be prepared or
conditioned
 The fish seed and brood fish are kept starving usually in a cloth (hapa)
or other container in a quite corner of the fish pond or in a relatively quiet
water in a canal or river for a period of time before transforming them to
the transport carrier
 Feed seed for long transportation have to be prepared or conditioned.
Keep fish in continuous flowing water without feeding for small fishes
6-12 hours and large fishes 24-48 hours. They excrete all the excreta,
hence no chance of excretion during transportation.
 Fry 8-23mm require 24 hour conditioning for transportation in a limited
volume of water (2ml) per fry
 The temperature of the conditioning water should not be high
 High oxygen contain (5-8 mg/l)
 The fish recover the handling effect, increased blood lactate level and
decrease blood ph become normal, excited high metabolic rates (o2
consumption, co2 production) become n0rmal
 The fish recover minor injury, mucus loss etc..
Method of packing and transport:
1. In open carrier, with or without artificial aeration/oxygenation
2. In sealed airtight carries with oxygen
Open carrier (container are not sealed): container may be earthen pots,
plastic pots or tin/metal container.
Earthen pots:
 It helps to keep the temperature of the water inside cool by means
of evaporative cooling.
 Generally 20-30 liters capacity are used for transportation of feed
seed.

 This are used for short transportation and need frequently
exchange of water in each hour.
 The temperature of the water is kept down by covering the vessels
by wet cloth.
 Dead fish must be removed immediately to avoid pollution of
water.
Plastic container:
 They are made by plastic. Transportation method is similar to earthen
method
Metal/ tin container:
 They are made by metals. Large sized aluminum vessels with wide
mouth are commonly used.
 Aluminum vessels are better than the earthen and plastic carrier because
they are not breakable.
 Transportation method is similar to earthen and plastic carrier.
Closed system:
In closed system the containers are sealed and contained with oxygen.
Container may be plastic bags, plastic tanks or aluminum and galvanized iron
sheet boxes.
a) Plastic bag:
 It is most common and widely used method for fish transportation.
 Plastic bags of 16-18 liter capacity is generally used.
 One third portion of the bags are filled with clean and cool water
and well-conditioned fish are then carefully introduced in required
number.

 The bag should be inflated with oxygen and the string is tied round
the bag tightly to prevent oxygen form leaking out.
 The bag should be checked for any leakage.
 It is advisable to keep each bag individually in wet jute bag to
prevent damage to the bag and maintain temperature during
transport.
b) Plastic tank:
 In this method, 200-500 liter plastic tanks are used with regular
supply of oxygen
 At least 5 mg/l oxygen concentration should be maintained at all
times.
 Higher oxygen levels near saturation level, may help fish cope with
the physiological stress of unavoidable ammonia build up,
especially during the long trip.
 In 500 liter tank, about 50000 to 100000 fish of 2-3 g size can be
transported for 8-10 hours.
Used of chemicals:
 The chemical method of treating the transport medium, aimed at
increasing the capacity volume of the transport units and preventing
physiological and health damage to the fish
 They include the use of loss of sensation (anesthetics), water hardening
and oxygen producing chemicals, bacteriostatic, buffering chemicals.
Use of fish tranquilizer: during transport sedation of the fish is desirable,
since oxygen consumption and CO2 and NH3 production are all decrease
Application of sodium chloride and calcium chloride: handling stress and
delayed mortality of fish can be decreased by the addition of sodium chloride
(NaCL) and calcium chloride (CACL2) to the transfer water.

Bacteriostatic chemicals: antibacterial (nitrofurazone or tetracycline) are also
used to check the development of bacteria in transport units.
Ammonia control: to control ammonia concentration in transport bags when
the transport is expected to be long.
Live transportation of table fish for sale:
Live fish selling is a recent technology in Nepal and has gained popularity due
to raised awareness towards fresh fish consumption. In Nepal, live fish
transportation for selling in market has been practiced since last decade, in
which, fish from remote village farms carried to urban market. Live fish are
transported in the plastic tanks of 500-1000 liter capacity water loaded on the
van or truck. The tank are supplied with oxygen using a cylinder. The tank can
hold up to 75 kg fish per tank.

Unit: 6 2022/7/31
Fish disease:
Disease is a departure from the typical normal state of health of fish or any
other animals. Disease may be classified as:
 Infectious disease when they are caused by microorganism such as
protozoa, fungi, virus, worms,
 Disease not caused by microorganism are noninfectious disease which
include nutritional deficiencies, dietary, toxicity and water quality
disease
Signs of sickness of fish:
 Fish becomes restless or abnormal
 There is a loss of balance and fish is unable to maintain its position in
the column of water
 Fish tends to line on its side either resting at the bottom or floating at the
surface
 Tail and fins do not seen to function normally with vigor
 Discoloration is common on the body
 Erosion of scale, fins, gills lamellae or parts of skin
 Gills appear pales
 Bloody and bulging eye
 Slowing down or complete stoppage of feeding.
According to Van Dugin (1956) a simple test for sick fish is as follows:
Hold the fish in position in hand under water and turn it on to its one side. If
he eye ball also turns following the turning of the body the fish is very sick.

1) Infectious disease:
a) Fungal disease: fungi are the parasite plants which usually live in
water or on the surface of fish. Given certain condition they are
able to invade the tissues themselves and cause large ulcers and
consequent loss of osmotic control.
Saprolegiasis (water mold disease): causative organism: Saprolegnia
parasitica
 This disease develops in injury, weakened, diseased or dead fish.
 Dead fish are the fertile medium for growth of saprolegnia
Disease symptoms:
 It is characteristics by wooly whitish or lightly brown blotches on the
skin, fins, eyes, mouth, gills, or on unfertilized eggs too
 The first indication of the fungal infection are usually dullness of the
body color
 Ulceration of skin exposed of jaw bones, blindness, inflammation of
liver and intestine
 Infected fish rub their body against hard surface due to irritation
 Fish show abnormal movement

Control measures:
 Individuals who gets mechanical injury during transportation or rough
handling are liable to fungal attack. Actions must be taken to avoid or
treat the primary cause like injuries, long storage in cement tanks and
unhealthy surrounding.
 If only a small part of skin is infected the fish can be taken out of water
and affected part s touched with 1:10 solution of iodine or with 1% of
potassium dichromate.
 Dip the diseased fish in 0.3 % common salt solution or 1:2000 solutions
of copper sulphate or in 1:1000 potassium permangate solution for about
5-10 minute
 Treat the fertilize egg with 3-5% formalin or 1-5% of salt for 10 minutes
2. branchiomycosis (gill rot disease):
Causative organism: Branchiomycosis sanguinis
It is a fungal disease affecting on gill tissue of the fish. It mainly occurs in
ponds with high organic matters load and high water temperature. Disease
spread quickly in hot season, when ambient temperature is above 25 degree C.
stress factor for this disease includes high temperature, low dissolved oxygen,
reduce water flow, overcrowded condition and high level of nutrition in water
and phytoplankton blooms
Disease symptoms:
 Respiratory distress in infected fish
 Due to blockage of blood vessels, hemostasis and thromboses occurs
causing necrosis of the gills filaments
 Area of the gills filaments turn brown due to ischemia
 Fish gather in groups at water inlet and finally die

Control measures and treatment:
 Strict sanitation and disinfection is essential for disease control.
Disinfection of pond and raceways using formalin and CuSO4 is
recommended
 Care must be taken to prevent the movement of disease fish to no
infected areas
 Pond should be dried and treated with malachite green at 0.1 ppm for
extended period of time or 0.3 ppm for 12 hours
 Disease fish can be given a quick dip (10-30 min) of 100 ppm CuSO4 or
3-5 % common salt solution
 Dead fish should be collected daily and burnt or deeply buried
3. Epizootic ulcerative syndrome (EUS): EUS is a seasonal epizootic
condition of freshwater fish of complexes infectious etiology. This disease is
also known as mycotic granulomatosis or red spot disease.it cause by
Aphanomyces invades.

EUS occurs mostly during periods of low temperature and after periods of
heavy rainfall. EUS is transmitted from one fish to another through the water
supply.
Disease symptoms:
 Development of red spot or small hemorrhagic lesions is seen on the skin
at initial stage which expand to form ulcers and eventually extensive
necrosis
 Granulomatous development on the internal organ which leading to
death
 Mass mortalities of fish occurs during an outbreak, especially in winter
and periods of heavy rainfall.
Control measures:
 Control of EUS is very difficult.
 Liming water and improving water supply, together with removal of
infected fish
 For complete recovery in case of heavy infestation, eradication is
considered as best way.
 Drying out and liming of ponds and disinfection of contaminated
equipment.
 Once the disease is eradicated good husbandry, surveillance and
biosecurity measure are necessary to prevent recurrence.

Bacterial disease:
Bacteria are highly celled, rod shaped organism which are always present in
water and they may also occur in small numbers on the skin or inside healthy
fish. Bacteria are responsible for many fish disease, especially those associated
with environmental stress such as handling. Bacteria are gram positive and
gram-negative group. Most of the fish pathogen are included in gram negative
group. There are several bacterial diseases like, tail rot or fin rot, furunculosis
and dropsy are common disease of cultivated fishes of Nepal.
1. Tail rot and fin rot:
Causative agent: flavibacterium columnaris or pseudomonas
fluorescens.
It is the most contagious bacterial disease of carps and results in the
purification of tail or other fins.
Clinical symptoms:
 A more or less distinct white line is seen at the margin of the fin in early
stages of the disease
 The line moves towards the base of the fin and the fin becomes torn and
after sometimes, the entire fin is destroyed.
 In severe stages, the infection may spread on the body of the fish and
invade the connective tissue too.

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