This document discusses trophic ecology of fishes. It defines trophic ecology as the study of feeding relationships between organisms in communities and ecosystems. Food webs and food chains are used to represent trophic relationships. The trophic level of an organism indicates its position in a food chain. Fishes can be categorized based on their feeding habits as herbivorous, carnivorous, or omnivorous. Polyculture is discussed as an effective way to utilize different trophic niches. Methods for analyzing fish gut contents and food habits are also outlined. Common skeletal deformities in fishes are described which can be caused by genetic or environmental factors like pollution.
Effect of environmental factors on fish egg and larvae pptAshish sahu
Introduction
Marine oil spills can affect the ecosystem both through their physical influence on the organisms and through the effect of the various chemicals in the oil. On the physical side, organisms can get caught in the viscous oil. Oil can also form a barrier to the surface, which can be damaging for some species of fish when they come to the surface to fill the swim bladder (Sundby et al., 2013). There are also several chemicals in the oil that can increase the mortality for eggs and larvae (Neff et al., 2000; Barron et al., 2004). Oil can stimulate the formation of marine snow (Passow et al., 2012) that may subsequently sinks to the ocean floor where it can impact the benthic fauna. If conditions become anoxic, oil in the sediment would decay more slowly since the biological remineralization of the oil is retarded in anoxic conditions. The use of dispersants to increase the rate of remineralization has also received attention in terms of its potential negative effect on the ecosystem (Kleindienst et al., 2015; Vikebø et al., 2015).
This study focuses on the seas around southern Norway (Figure 1), where the currents are dominated by the Norwegian Coastal Current (NCC) that flows along the coast all the way from the Skagerrak to northern Norway. This current would primarily transport oil spills, eggs, and larvae along the coast. In the northern part of the area, the NCC flows side by side with the Norwegian Atlantic Current (NAC), which is a more saline current also directed northwards. Strong winds of variable directions and high waves occur frequently, particularly during winter, and contribute to the upper layer drift. The area has strong mesoscale activity, particularly in the frontal region between the fresher NCC and the eastern branch of the NAC, and thus it is difficult to predict the local currents on short time scales. The tidal amplitudes, and consequently the tidal currents, are small (<1.0 m) in the southern parts of Norway, but become larger in northern Norway.
A short description about magur fish.The walking catfish (Clarias batrachus) is a species of freshwater airbreathing catfish native to Southeast Asia, but also introduced outside its native range where it is considered an invasive species. It is named for its ability to "walk" across dry land, to find food or suitable environments. While it does not truly walk as most bipeds or quadrupeds do, it has the ability to use its pectoral fins to keep it upright as it makes a wiggling motion with snakelike movements.[2] This fish normally lives in slow-moving and often stagnant waters in ponds, swamps, streams and rivers, flooded rice paddies or temporary pools which may dry up
Modern developments in transport technology are from two levels; one is from an understanding of internal physiological mechanisms of the fish and the optimal requirements, ensuring maximum survival of fish under transport and the other is from a study of the environmental parameters of the medium in which fish are transported. Under anaesthesia fish can be transported without water even, provided the skin and gills are kept moist under low temperature. The cryopreservation of fish sperm for use at any convenient time can be referred to here, though this would concern seed production more directly than live seed transport.
Effect of environmental factors on fish egg and larvae pptAshish sahu
Introduction
Marine oil spills can affect the ecosystem both through their physical influence on the organisms and through the effect of the various chemicals in the oil. On the physical side, organisms can get caught in the viscous oil. Oil can also form a barrier to the surface, which can be damaging for some species of fish when they come to the surface to fill the swim bladder (Sundby et al., 2013). There are also several chemicals in the oil that can increase the mortality for eggs and larvae (Neff et al., 2000; Barron et al., 2004). Oil can stimulate the formation of marine snow (Passow et al., 2012) that may subsequently sinks to the ocean floor where it can impact the benthic fauna. If conditions become anoxic, oil in the sediment would decay more slowly since the biological remineralization of the oil is retarded in anoxic conditions. The use of dispersants to increase the rate of remineralization has also received attention in terms of its potential negative effect on the ecosystem (Kleindienst et al., 2015; Vikebø et al., 2015).
This study focuses on the seas around southern Norway (Figure 1), where the currents are dominated by the Norwegian Coastal Current (NCC) that flows along the coast all the way from the Skagerrak to northern Norway. This current would primarily transport oil spills, eggs, and larvae along the coast. In the northern part of the area, the NCC flows side by side with the Norwegian Atlantic Current (NAC), which is a more saline current also directed northwards. Strong winds of variable directions and high waves occur frequently, particularly during winter, and contribute to the upper layer drift. The area has strong mesoscale activity, particularly in the frontal region between the fresher NCC and the eastern branch of the NAC, and thus it is difficult to predict the local currents on short time scales. The tidal amplitudes, and consequently the tidal currents, are small (<1.0 m) in the southern parts of Norway, but become larger in northern Norway.
A short description about magur fish.The walking catfish (Clarias batrachus) is a species of freshwater airbreathing catfish native to Southeast Asia, but also introduced outside its native range where it is considered an invasive species. It is named for its ability to "walk" across dry land, to find food or suitable environments. While it does not truly walk as most bipeds or quadrupeds do, it has the ability to use its pectoral fins to keep it upright as it makes a wiggling motion with snakelike movements.[2] This fish normally lives in slow-moving and often stagnant waters in ponds, swamps, streams and rivers, flooded rice paddies or temporary pools which may dry up
Modern developments in transport technology are from two levels; one is from an understanding of internal physiological mechanisms of the fish and the optimal requirements, ensuring maximum survival of fish under transport and the other is from a study of the environmental parameters of the medium in which fish are transported. Under anaesthesia fish can be transported without water even, provided the skin and gills are kept moist under low temperature. The cryopreservation of fish sperm for use at any convenient time can be referred to here, though this would concern seed production more directly than live seed transport.
The transfer of fish seed from the hatchery or place of collection to the rearing pond is called transport of fish seed. The seed fish include fry and fingerlings.
Carps form the mainstay of aquaculture in India contributing over 85% of the total aquaculture production There are 61,259 species of vertebrates recognized world; over 30,700 are fish species of which 8,411 ore fresh water while 11,650 are marine. In India 2,163 spp. are fin fishes have been recorded from upland cold water (157; 7.26%) warm water of the plain (54; 20.99%), Brackish water (182; 8.41%) and marine environment (1,370; 63.43%). Some of these species are cultured at commercial level which covering a lot varieties of fin fishes The three Indian major carps, namely Catla (Catla catla), Rohu (Labeo rohita) and Mrigal (Cirrhinus mrigal) contribute the bulk of production to the extent of 75 to85 percent of the total fresh water fish production, the three exotic carp such as Silver carp (Hypophthalmichthys molitrix) and Common carp (Cyprinus carpio ), Grass carp (Ctenopharyngodon idella )form the second important group to incorporate several other medium and minor carp and into the carp poly culture system several method were used because of their region specific consumer preference and higher market demand.
History
Carp culture in India was restricted only to a homestead backyard pond activity in west Bengal and Odisha until late 1950 s with seed from riverine sources as the only input resulting low level of production the technological breakthrough breeding of carp through hypophysation in 1957 freshwater aquaculture of the country the country till 1984 virtually laid the foundation of scientific carp farming in the country.
Important characteristics of Indian major carps:-
Indian major carp grow fast and can reproduce even in artificial ponds. They feed upon phytoplankton, zooplankton, decaying organic matter, aquatic plant etc. stomach is absent in the alimentary canal of the major carps. Three types of Indian major carps are cultured in
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Fish usually migrate to feed or to reproduce, but in other cases the reasons are unclear.
Migrations involve the fish moving from one part of a water body to another on a regular basis. Some particular types of migration are anadromous, in which adult fish live in the sea and migrate into fresh water to spawn, and catadromous, in which adult fish live in fresh water and migrate into salt water to spawn.
Marine forage fish often make large migrations between their spawning, feeding and nursery grounds. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements may partly be linked to the fact that the fish cannot identify their own offspring and moving in this way prevents cannibalism. Some species have been described by the United Nations Convention on the Law of the Sea as highly migratory species. These are large pelagic fish that move in and out of the exclusive economic zones of different nations, and these are covered differently in the treaty from other fish.
Salmon and striped bass are well-known anadromous fish, and freshwater eels are catadromous fish that make large migrations. The bull shark is a euryhaline species that moves at will from fresh to salt water, and many marine fish make a diel vertical migration, rising to the surface to feed at night and sinking to lower layers of the ocean by day. Some fish such as tuna move to the north and south at different times of year following temperature gradients. The patterns of migration are of great interest to the fishing industry. Movements of fish in fresh water also occur; often the fish swim upriver to spawn, and these traditional movements are increasingly being disrupted by the building of dams.
Fertilized fish eggs are known as Fish seeds. In simple words, they are the baby fishes used for seeding new Ponds in fisheries. Fish seed transportation is a process by which transfer of fish seed from the hatchery or place of collection to the rearing ponds.
The transfer of fish seed from the hatchery or place of collection to the rearing pond is called transport of fish seed. The seed fish include fry and fingerlings.
Carps form the mainstay of aquaculture in India contributing over 85% of the total aquaculture production There are 61,259 species of vertebrates recognized world; over 30,700 are fish species of which 8,411 ore fresh water while 11,650 are marine. In India 2,163 spp. are fin fishes have been recorded from upland cold water (157; 7.26%) warm water of the plain (54; 20.99%), Brackish water (182; 8.41%) and marine environment (1,370; 63.43%). Some of these species are cultured at commercial level which covering a lot varieties of fin fishes The three Indian major carps, namely Catla (Catla catla), Rohu (Labeo rohita) and Mrigal (Cirrhinus mrigal) contribute the bulk of production to the extent of 75 to85 percent of the total fresh water fish production, the three exotic carp such as Silver carp (Hypophthalmichthys molitrix) and Common carp (Cyprinus carpio ), Grass carp (Ctenopharyngodon idella )form the second important group to incorporate several other medium and minor carp and into the carp poly culture system several method were used because of their region specific consumer preference and higher market demand.
History
Carp culture in India was restricted only to a homestead backyard pond activity in west Bengal and Odisha until late 1950 s with seed from riverine sources as the only input resulting low level of production the technological breakthrough breeding of carp through hypophysation in 1957 freshwater aquaculture of the country the country till 1984 virtually laid the foundation of scientific carp farming in the country.
Important characteristics of Indian major carps:-
Indian major carp grow fast and can reproduce even in artificial ponds. They feed upon phytoplankton, zooplankton, decaying organic matter, aquatic plant etc. stomach is absent in the alimentary canal of the major carps. Three types of Indian major carps are cultured in
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Fish usually migrate to feed or to reproduce, but in other cases the reasons are unclear.
Migrations involve the fish moving from one part of a water body to another on a regular basis. Some particular types of migration are anadromous, in which adult fish live in the sea and migrate into fresh water to spawn, and catadromous, in which adult fish live in fresh water and migrate into salt water to spawn.
Marine forage fish often make large migrations between their spawning, feeding and nursery grounds. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements may partly be linked to the fact that the fish cannot identify their own offspring and moving in this way prevents cannibalism. Some species have been described by the United Nations Convention on the Law of the Sea as highly migratory species. These are large pelagic fish that move in and out of the exclusive economic zones of different nations, and these are covered differently in the treaty from other fish.
Salmon and striped bass are well-known anadromous fish, and freshwater eels are catadromous fish that make large migrations. The bull shark is a euryhaline species that moves at will from fresh to salt water, and many marine fish make a diel vertical migration, rising to the surface to feed at night and sinking to lower layers of the ocean by day. Some fish such as tuna move to the north and south at different times of year following temperature gradients. The patterns of migration are of great interest to the fishing industry. Movements of fish in fresh water also occur; often the fish swim upriver to spawn, and these traditional movements are increasingly being disrupted by the building of dams.
Fertilized fish eggs are known as Fish seeds. In simple words, they are the baby fishes used for seeding new Ponds in fisheries. Fish seed transportation is a process by which transfer of fish seed from the hatchery or place of collection to the rearing ponds.
The monitoring of what happens within a pen at a fish farm has progressively become a greater necessity for fisheries. As the complexity and importance of monitoring the relevant behaviour of the fish developed so did the engineering solutions.
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Selection of the pond site is one of the most important steps in construction. A good pond site contains (l) Level topography that provides for economical construction, (2) soil with sufficient clay to hold water and (3) an adequate water supply. Before making the final site selection, one should examine all potential sites considering economics, accessibility and safety. Economically speaking, construct a pond that provides the largest volume of water with the least amount of landfill. Liability is a final consideration. For example, what would happen if the dam failed causing loss of life or injury? The pond owner is normally held liable for downstream flooding and related damages caused by dam failure.
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and insect parts in Mystus bleekeri have been contained the maximum percentage (34.84%) of the content under
frequency of occurrence method followed by algae and protozoan with 20.76%, Molluscs with 18.37%, plant materials
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Mystus vittatus fed on similar food items. These were mainly crustaceans, molluscans, fish remains and macrophytes.
Other food items include algae, detritus, sand grains. These four species are omnivorous and occupy the same ecological
niche.
Key-words- Cat fish, Food and feeding, Frequency, Numerical method
Fish culture is classified based on the number of fish species as monoculture and polyculture. This is the culture of single species of fish in a pond or tank. The culture of trout, tilapia, catfish , carps are typical examples of monoculture.
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Trophic ecology of fishes,polyculture, fish food analysis and fish deformities by SYED AASIM HAQ
1. Trophic Ecology Of Fishes
SubmittedBy;
SYEDAASIMHAQ
ROLLNo.
A.M.U
M.Sc.ZOOLOGY
2. Trophic Ecology Of Fishes
The study of the feeding relationships of organisms in
communities and ecosystems is known as trophic
ecology.
Focus on the interplay between feeding relationships
and ecosystem attributes such as nutrient cycling,
physical disturbance, or the rate of tissue
production by plants and the accrual of detritus.
Trophic relationships can be represented
as a Food web or as a Food chain.
3. Food webs depict trophic links between
all species sampled in a habitat, whereas food
chains simplify this complexity into linear
arrays of interactions among trophic levels.
These trophic levels are not always simple integers, as
organisms often feed at more than one trophic level.
4. Three fundamental questions in the field of
trophic ecology are important:
(1) What is the relationship between the
length of food chains and plant biomass
(2) How do resource supply to producer and
resource demand by predators determine the relative
abundance of organisms at each trophic level in
a food chain
(3) How long are real food chains, and what
factors limit food chain length
5. Trophic Level And Food Chain
The trophic level of an organism is the position it
occupies in a food chain.These are
Primary producers; are principally green plants and
certain bacteria. They convert solar energy into
organic energy.
Consumers; Above producers who ingest live plants
or the prey of others.
Decomposers; such as, bacteria, molds, and fungi
make use of energy stored in already dead plant and
animal tissues.
6. Further trophic levels are numbered
subsequently according to how far the organism
is along the food chain.
Level 1: Plants and algae make their own food and are
called primary producers.
Level 2: Herbivores eat plants and are called primary
consumers.
Level 3: Carnivores which eat herbivores are called
secondary consumers.
Level 4: Carnivores which eat other carnivores are
called tertiary consumers.
Level 5: Top Carnivore which have no predators and
are at the top of the food chain
7.
8. Feeding In Fishes
Food eaten by various species of fishes has been
divided into four categories;
Main Food; natural and preferred by the fish.
Secondary Food; consumed by the fish when
available.
Incidental Food; enters the gut by chance with
others.
Emergency Food; Taken only under unfavorable
conditions when basic food is not available.
11. Other specific categories are ;
Plankton feeders
Insectivorous
Crustacean Feeders
Mollusk Feeders
Larvivorous
Piscivorous etc
12. Fresh water fishes can also be divided into three groups
on the basis of their ecological zone of feeding
Surface Feeders ( Catla catla , Hypophthalmichthys
molitrix, Hilsa hilsa etc)
Column Feeders ( Labeo rohita , Wallago attu , tor
tor etc )
Bottom Feeders ( Labeo calbasu , Labeo bata
Cirrhinus mirgala etc )
15. Polyculture
It is the practice of culturing more than one species of
aquatic organism in the same pond.
The motivating principle is that fish production in
ponds may be maximized by raising a combination of
species having different food habits.
Polyculture of fish is based on the concept of total
utilization of different trophic and spatial niches of a
pond in order to obtain maximum fish production per
unit area.
17. In India polyculture with carps (IMC) is widely being
carried out.
These include Catla catla , Labeo rohita and Cirrhinus
mirgala.
These are stocked at the ratio of 3:3:4 respectively.
Besides these , polyculture with Chinese carps (silver
carp , grass crap and common carp) is also being
carried out.
18. Advantages
Maximum fish production is possible in polyculture.
More profitable and easy to maintain.
More Economic.
Different fish species cultivating in a single pond.
More fish can be cultivated and produced from short
place.
Almost all the available niche is being utilized in a
single pond. More efficient use of natural resources.
19. Factors Affecting Species
selection
Water Temperature
Market value of fish.
Feeding habits of fish.
Pond fertilization practice.
Tolerance to pond conditions.
Potential of uncontrolled swamping in grow out pond.
21. Food Habit Analysis
Description of fish diets and feeding habits provides
basis for understanding trophic interactions in aquatic
food webs.
Diets of fishes represent an integration of many
important ecological components that include the
behavior, condition, habitat use and inter/intra
specific interactions.
22. Gut Analysis
Gut content analysis provides important insight into
fish feeding patterns and quantitative assessment of
food habits is an important aspect of fisheries
management.
All items in gut should be sampled.
If live fish is sacrificed the stomach contents to be
preserved immediately to prevent digestion (5%
neutralized formalin).
23. Make a longitudinal cut along the stomach and
transferred to a petri dish.
Remove excess formalin and keep under binocular
microscope and identify.
Only the immediate foregut to be sampled.
For a better understanding of diet data and for
accurate interpretation of fish feeding patterns, time
of day, sampling location, prey availability and even
the type of collecting gear used need to be considered
before initiating a diet study or analyzing existing diet
data.
25. Methods
Qualitative ; It involves complete identification of
gut contents. It needs extensive experience and good
support of references.
Quantitative ; It includes Numerical ,Volumetric
and Gravimetric methods.
26. 1) Numerical Methods
(Only counts of prey items are considered)
Frequency of Occurrence
Number method
Dominance method
Points method
27. i) Frequency of Occurrence
The number of stomachs in which each item occurs is
recorded and expressed as a percentage of the total
number of stomachs examined.
a) It provide information on how often (or not) a
particular prey item was eaten
b) But no indication of the relative importance of
prey to overall diet
28. ii) Number method
The number of individual of each food type in each
stomach is counted and expressed as a percentage of
the total number of food items in the sample studied,
or as a percentage of the gut contents of each specimen
examined, from which the total percentage
composition is estimated.
a)Common method for the analysis of planktivores
b)Drawback: Small prey can represent dominant
component of the diet
29. iii) Dominance Method
The stomach contents comprising the main bulk of the
food materials present, is determined and the number
of fish in which each such dominant food material is
present is expressed as a percentage of the total
number of fishes examined.
a)Drawback: It yield only a rough picture of dietary of
a fish.
30. iv) Points method
Food items are allotted a certain no. of points based on
rough counts and judgments by the eye. In a more
modified form, the food items are classified as ‘very
common’, ‘common’, ‘frequent’, ‘rare’, etc.,
a)Food items are classified as common, very common,
frequent, rare etc
b) Personal bias.
31. 2) Volumetric Method
(Best method for herbivores and omnivores where
other methods are meaningless)
1)Point method; Prey items are allotted certain points based
on its volume. Very useful for Omnivores and herbivores
2) Eye estimation
3)Displacement method; Displaced volume of each prey
items is measured in a graduated cylinder. Most accurate
among the three and is suitable for carnivore.
32. 3) Gravimetric methods
The gravimetric method consists of the estimation of
the weight of each of the food items, which is usually
expressed as percentages of the weight of the total gut
contents as in other quantitative methods.
a)Dry weight – More time consuming
b)Wet weight- Common method for
Carnivores
34. A deformity is a major abnormality in the shape of a
body part or organ compared to the normal shape of
that part.
Deformities in various parts of a fish’s anatomy can
occur in just about any part of the body, but they are
mostly associated with the calcified skeletal structures.
Thus, those structures which commonly exhibit
defects include the vertebral column (backbone), the
skull and various fins.
To a lesser degree, defects are evident in the internal
organs.
35. Cause of Deformities
Genetic (congenitally )
Environmental factors ;
like pollution , radiations, temperature, altitude ,
chemical factors , pathogens , stress , nutrient deficiency
etc
36. Skeletal Abnormalities
Skeletal anomalies. particularly those of the spinal
column are commonly observed in fish
Generally caused by effects of environmental factors
such as temperature. salinity. dissolved oxygen.
radiation, dietary deficiencies. and toxic chemicals.
For example, increased percentages of abnormal
embryos and larvae of Atlantic herring, Clupea
harengus, resulted from experimental exposures to
sulfuric acid waste water (Kinne and Rosenthal 19671
and to the algicides 2,4- and 2.5 dinitrophenol
(Rosenthal and Stelzer 1970).
37. Exposure of fry to very low concentrations of DDT
«1 ppb) produced anomalies in fin rays (Valentine and
Soule 1973).
It is seen that high chlorinated hydrocarbon and
heavy metal levels are seemed to be reasons for the
higher prevalence's of anomalies particularly gill raker
deformities in fish from the southern California coast.
Vertebral deformities in herring fish taken in waters
around the British Isles showed the predominant
abnormality was a cluster of two or three incomplete
vertebrae located near the pelvic fins or anus (van de
Kamp).
38. Several types of abnormalities are reported from various
regions of the world by various authors. Some of the
evidences of abnormalities reported are sites as;
Skeletal abnormalities in mullet and eight other species
from the Inland Sea of Japan were reported by Matsusato
(1973).
Komada (1974) and Ueki and Sugiyama (1976) observed
increasing numbers of malformed sweetfish or ayu,
Plecoglossus altivelis , in rivers and culture farms of
japan.
Gabriel (1944) noted abnormities in vertebrae of Fundulus
heteroclitus due to temperature changes
39. Mottley (1937) found anomalies in vertebral numbers
of trout due to temperature (and possible oxygen).
Hubbs (1959) found high prevalence's of vertebral
abnormalities in Gambusia affinis from Texas warm
springs due to high temperature.
Long-term (10 wk) exposure of minnows (Phoxinus
phoxinus) to sub lethal concentrations of zinc and
cadmium resulted in hemorrhaging, spinal curvatures,
and vertebral fractures, particularly in the caudal
region, in up to 70% of individuals (Bengtsson 1975).
Spinal curvatures and muscle atrophy were produced
in rainbow trout by chronic exposure to lead
(Bengtsoon).
40. In earlier studies, summarized by Bengtsson, exposure
to sub lethal concentrations of Malathion, parathion,
and certain other organophosphorus pesticides
produced vertebral damage or spinal flexures in
several fish species.
Couch et al have also found that trifluralin (Treflan)
induced extensive osseous hyperplasia in vertebrae of
sheepshead minnows when life history stages from
zygote to 28-day juveniles were exposed to 25-50 ppb
trifluralin.
43. Certain Chemicals and their effects
DDT: Necrosis of hepatic cells; lymphocytic infiltration of
intestinal lamina propria; possible degeneration of kidney
tubules.
Carbaryl (Sevin): Intramuscular hemorrhages adjacent to
vertebral column: atrophy of the lateral line musculature;
myxomatous degeneration of fat; vacuoles within the optic
tectum of the brain.
Malathion: Subcutaneous hemorrhages at the bases of pectoral
fins.
Endosulfan (Thiodan): Hyperemia of intestine and brain;
adrenal cortical hyperplasia. 2,4-D: Striking degree of brain
hyperemia; hyperemia of intestine.
Atrazine: Marked edema of all tissues; changes in skin
pigmentation.
44. Reference
Pollution-Associated Diseases And Abnormalities of Fish and
Shellfish: A Review CARL J. SINDERMANN
Textbook of Fish Biology and Fisheries, Khanna, S S & H R Singh.
Economic zoology by R.C.SOBTI.
www.ncbi.nlm.nih.gov
www.eprints.cmfri.org.in
Wikipedia
Comparative Physiology , Developmental Biology and Ecology by
ASHOK SABHARWAl.
www.fao.org