Fish disease management guide

ICAR-CIFA Grow Fish… Grow with Fish…
How to Manage Disease Problems in
Aquaculture
Dr. S. S. Mishra
डॉ एस.एस. ममश्रा
Principal Scientist & Head
प्रधान वैऻाननक एवं प्रभागाध्यऺ
Fish Health Management Division
मत्स्य ्वा््य प्रबंधन प्रभाग
ICAR- Central Institute of Freshwater Aquaculture
क
ें द्रीय मीठाजऱ जीवऩाऱन अनुसंधान सं्थान
Kausalyaganga, Bhubaneswar – 751002, Odisha
कौसल्यागंग, भुवनेश्वर, ओडिशा
Mob: 7894281261; Email: ssmishra60@gmail.com

Dr. S. S. Mishra, Head, FHMD
Fish Disease Major cause of Concern
• Fish Disease: Major Constraint to Aquaculture
Development – Doubling fish production rldide
• Nearly 10-15% Production loss: due to disease
• More is the intensity of culture: More chances of
disease occurrence
• Bioflock Culture: More cases of disease
• Disease can be of in terms of Morbidity, mortality,
Fish-kills

i) Caused by Infectious agents (Biological):
Bacteria, Viruses, Fungi and Parasites
ii) Non- infectious agents:
• Physical agents: Extreme temp. changes, Radiation
• Chemical agents: Env. contaminants, Toxins,
Nutritional imbalances, Drug and chemical etc.
• Non- infectious factors: more important than
infectious factors
Fish Disease/ Mortality : 2 Types

मछऱी में रोग क
ै से होता है??
How Disease Occurs in Fish ??
Interaction of Three Factors:
• Optimum water quality+ Pathogen=
No Disease
• Sub-Optimum Water quality +
Pathogen + Healthy Host= No
disease
• Poor water quality+ Stressed Fish +
Pathogen= Disease induction

Factors responsible for inducing stress
to cultured fish
• Poor water quality: High organic load, low
Alkalinity
• Lack of proper feeding: emaciation
• Sudden change in Env. Temperature
• Overstocking: More than carrying capacity
• Improper handling: Netting
• Drugs, Chemicals and sanitizers applied in
pond

Water quality: Very imp. Factor but often
neglected
• Dissolved gasses including oxygen (DO)
and carbon dioxide (CO2)
• Waste products like Ammonia and Nitrite
• Alkalinity for pH control
• Calcium and Magnesium (hardness) and salt
levels
Water quality

Optimum water quality to be maintained in a
culture pond
• pH: 7.5 – 8.5
• क
ु ऱ ऺारीयता (Total Alkalinity):
 Grow-out: >100– 250 ppm
 Fry Stocking : 80-100ppm
 Fingerling Stocking 100 ppm
 In Hatcheries: Spawn: 60-70 ppm
• क
ु ऱ कठोरता (Total hardness): >100– 250 ppm
• अमोननया (Ammonia) : < 1.0 ppm
• घुमऱत ऑक्सीजन (DO): > 3 ppm

How to correct water Alkalinity
• If low alkalinity: Add Lime (CaO)
• If High alkalinity: Add Alum
• Dose Calculation for Lime: If Alkalinity is 60 ppm
(But requirement 100 ppm)
• Dose= Difference x 10/Ha/M water depth
100-60= 40x10= 400kg/Ha/M (Give in 100
kg divided Doses
 Dose for Alum: (If alkalinity is 100 and want to make
60 ppm)
 Difference x 15/Ha/M water depth
= 40x15 = 600kg/ Ha/M

2. Quality Feed:
• Vitamin- Minerals & Micronutrients
Malnutrition causes: Scale loss
deformity, slow growth and fish
become prone to disease/
pathogen attack
• Nutritionally balanced feed: संतुमऱत आहार
It determines the health status of fish

Types of feeding
• Broadcasting: Major loss (50-60%),
increase organic load
• In trays/ Handi: Improper distribution
• Hanging bags/ Buckets

Recommended Stocking density in ponds:
Always stock as per the carrying
capacity of culture system
Spawn: 20 lakhs/ Acre
Fingerlings) 4000 nos/Acre
Stunted Yearlings: 2000 nos/ acre
Proper Sticking in a pond

Biological Agents of Disease
• Bacterial
• Viral
• Fungal
• Parasitic
They are often called infectious
disease agents

Variation of disease occurrence pattern in Different
Fish culture Systems
Pond Culture, Open Water, Cage Culture, Bioflock system

• Red disease : Multiple
pathogens involved
• Several members of the
Genus Aeromonas:
Aeromonas hydrophila, A.
sobria, A. caviae, A.veronii
etc. are associated
Common Bacterial Diseases of Fish in Cultured
ponds:

If neglected: become
Ulcerative- High mortality
Poor water quality: Main
inducing factor

Tail rot- Fin Rot
• Bacterial disease, typical
symptoms like erosion of fins,
sometime total loss of fins.
• Multiple bacterial pathogens
involved
• Poor water quality in culture ponds
is the main inducing factor.

Columnaris disease
Imp. Bacterial disease caused by- Flavobacterium
columnare - earlier known as Cytophaga columnaris
and Flexibacter columnaris.
• Major disease in warm and cold water
fish: All size age groups affected
• Mainly due to high organic load in
culture system
• Yellowish discoloration of body
muscle & gills
• Ulcers on Back: Saddle disease

Columnaris Disease Contd…
Body Haremorrhages,
Gill & Muscle necrosis

Dropsy
ICAR-CIFA Grow Fish… Grow with
• Dropsy: Also called Oedema fish
disease”.
• Bacterial infection of the Kidneys :
Aeromonas spp.
• Swelling in the abdomen due to fluid
retention .
• Internal organs are damaged
• Poor water quality – predisposing
factor

Bacterial Septicaemia
Bacterial Septicaemia:
(Haemorrhagic Septicaemia)
• Caused By: Motile Aeromonas &
Pseudomonas spp.
• Ruffled scales: Fluid accumulation
Underlying skin
• High mortality: 70-80%

Bacterial Gill Disease
• BGD is caused by a number of
different bacteria that infect the gills
of fish.
• Presence of large numbers of
filamentous bacteria on the gills
accompanied by clubbing and fusing
of the gill filaments.
• Flavobacterium
branchiophilum

Streptococcal Eye Disease of Fish:
Cloudy eye
Streptococcal diseases of fish are not
common; however, when they do
occur, significant mortality can result.
Symptoms:
Erratic swimming, uni- or bilateral
exophthalmia ("pop-eye" in one or
both eyes); corneal opacity (whitish
eyes); hemorrhages in or around the eye,
the gill plate, base of the fins, vent/anus,

Disease problems in Cage Culture

Fungal Disease
• Net is the main Source of Fungal growth
• Clogged/Dirty nets/ Deposition of feed,
Organic matters

Bioflock System
• Highly stressful environment
• Need 24x7 attention like RAS

Stress induced diseases :
Sometimes unknown etiologies

Disease Diagnosis & Control
Methods to be followed
1. On-site observation
2. Historical Data collection
3. Water quality estimation
4. Gross pathology
5. Sample collection for
i)Water quality & Microbiological analysis
ii)Virology/ Histology
iii)Parasitology

On-site investigation:
• Visit the site- Early in the morning bore Sunrise
• Observation:
Any change in behaviour including:
 Fish congregating at the surface or at the
water’s edge
 Fish “flashing” (rubbing against the bottom or
other hard surfaces)- Parasitic
 Reflex action: Response to sound
 Feed Response: A reduction in feed
consumption not clearly related to low
oxygen or temperature changes

Gross observation of Fish:
• Any lesions/ Injury/ Growth
• Any parasite
• Change in gill colour/ growth on
fish gill
Measure environmental conditions
(Water temperature, Alkalinity,
Ammonia, DO etc.)

Treatment of bacterial diseases:
• Consult the Expert: Dist. Fisheries Officials/
Scientists, Fish Disease specialists
• First test water quality: Correct water Alkalinity by
application of Lime CaO
• Intimate about the pond condition, culture
species details, etc.
• Various Antiseptics/ drugs & Chemicals available
in the market
• Follow USFDA/ Govt. guidelines
• Give recommended Withdrawal period for each
treatment: Very important

Common Antiseptics for bacterial
disease:
i) Benzalkonium chloride (BKC)
ii) Idophore
iii) Acriflavine HCl
iii) CIFAX :
iv) Didecyle dimethyl ammonium
Chloride (Sokrena WS)
Treatment for Bacterial Diseases
Antiseptics in water + Oral Antibiotics:
Gives Best results

Antibiotics for Use in aquaculture: Follow
USFDA/ Govt. guidelines
• Oxytetracycline
75mg/kg fish biomass per day
for consecutive 7-10 days
through feed,
• Co-trimazine (Trimethoprim
and Sulphadiazine) 30mg/kg
fish biomass per day for
consecutive 10 days through
feed

Antibacterial agents recommended for use in aquaculture
Agent Dosage and route Comments
Acriflavine 500mg/l x 30 min bath
5-10 mg/l prolonged bath
Skin bacterial infections
Chloramine -T 15.0-20mg/l for prolonged
bath, repeat after 48 h
Treatment of bacterial gill
disease, fin rot
Methylene blue 2mg/l prolonged bath Skin bacterial infections,
Nifurpiriniol
(Furanace)
1-2mg/l x 30 min to 6 h bath
0.1mg/l Prolonged bath
4-10 mg/kg in feed for 5 days
Generalized bacterial
infection
Oxytetracycline 10-100mg/l x 1 h bath
55-83 mg/l in feed x 10 days
Generalized infections
Potassium
permanganate
5mg/l x 30-60 min bath
2 mg/l permanent bath
Broad spectrum anti-septic
Povidone-iodine Topical application to wounds Broad spectrum activity
Sulphadimethoxine
and ormetoprim
50mg/kg in feed x 5 days Broad spectrum activity

Antibiotics and other pharmacologically active substances banned for use in aquaculture in
India, as per recommendation of Coastal Aquaculture Authority/MPEDA
1. Chloramphenicol 11. Dimetridazole
2 Nitrofurans including: Furaltadone,
Furazolidone, Furylfuramide,Nifuratel,
Nifuroxime, Nifurprazine,
Nitrofurantoin, Nitrofurazone
12. Sulfonamide drugs (except
approved Sulfadimethoxine,
Sulfabromomethazine and
Sulfaethoxypyridazine)
3. Neomycin 13. Ronidazole
4. Nalidixic acid 14. Ipronidazole
5. Sulphamethoxazole 15. Other nitroimidazoles
6. Aristolochia spp and preparations
thereof
16. Clenbuterol
7. Chloroform 17. Diethylstilbestrol (DES)
8. Chlorpromazine 18. Metronidazole
9. Colchicine 19. Fluroquinolones
10. Dapsone 20. Glycopeptides

Fungal Disease
• Fungal infections: called mycoses
• More occurrence in Aquarium Fishes &
Cage culture system
• Fungal spores are found in all fish ponds
and create problems in stressed fish.
• Poor water quality can also lead to an
increase in fungal infections.
3 Important:
i) Saprolegniasis/Cotton wool disease:
ii) Branchiomycosis (Gill rot disease)
iii) Epizootic Ulcerative syndrome

1. Saprolegniasis /Cotton wool disease:
Caused by Saprolegnia parasitica,
Family: Saprolegniaceae
• Fish fungus appears as grey or
white patches on the skin/gills.
• They may become brown/green as
they trap sediment.
• Normally establishes as small,
focal infections that then spread
rapidly over the body or gills.

2. Branchiomyces - Gill Rot Disease
• Caused by Branchiomyces sanguinis
and Branchiomyces demigrans.
• Necrosis of the gills, Fungal growth
• Stress factors: Over crowded
conditions, High levels of
nutrients/ organic load in the water
and phytoplankton blooms.

3. Epizootic Ulcerative syndrome (EUS)
Causative agent: Aphanomyces
invadans, a fungus primary
causative factor.
• Localized red spots appear on
the body that spread to become
ulcers and deep sores.
• Secondary bacterial infections
are quite common.
• Causes economic loss as the
affected fish has no or low
consumer preference.

Treatment of fungal Diseases:
• Bath treatment to adult fishes with
Potassium permanganate @ 160 mg/l.
• Malachite green (??)
Fish eggs: at 50mg/100l (0.5 ppm)
Broodstock : 5-6g/100l as dip for 30 sec.
Fish culture : 50g/acre
• Copper Sulpahte: @50-100 mg/100l (0.5 -
1.0 ppm)

• CIFAX: Very useful in EUS:
400 ml/ acre in pond as prophylactic
1.0 lit/acre treatment as single dose
• Dip treatment with pure iodine /
Idophores at 50-100 ppm for 10-15
mins.
• Fluconazole/ Itraconazole: 100mg/
100kg feed, 7 days

Monogenian trematodes
A.Gyrodactylus spp.
:knows as Skin flukes
B. Dactylogyrus spp. :
known as Gill flukes
Parasitic Diseases of Fish

B) Dactylogyrus spp. : known as Gill flukes
A group of flukes seen under microscope
Gill fluke-stained

Crustacean parasites
Learneae, Argulous, Ergasilus (gill lice)
a) Learneae spp

Argulus)
Most important fish parasite: Skin,
Gills, fins, tissue damage, ulcers
Gross
observation
Visible
under
microscope

Controlling Egg
hatching is important

Ergasilus, 0.9-1.5 mm long
Parasite attaches to the gills and
body surface of the host. White to
dark brown copepods, <2 mm long,
some with 2 white elongated egg
sacs are firmly attached to the gills.
Affected fish have emaciated body.

Myxozoan infestation :
• Myxobolus Cysts seen on skin, gill, Fin
•Under heavy infestation they cause mortality.
Gills heavily infested with cysts
L. rohita : cysts on Caudal fin

Myxobolus cysts: Different magnifications

Trichodina
Trichodina (45-78 μm diameter), The parasites are attached mainly
on the gills and skin of the host. Affected fish appear weak with
excessive mucus production and with frayed fins.

Ichthyophthiriosis (Ich) : White spot disease
•Caused by ciliate protozoan Ichthyophthirius multifiliis.
•Size: 0.5-1.5 mm wide, Characterized by its horseshoe shaped
macronucleus.
Visible white spot on the body
surface

Treatment for parasitic diseases :
Various Anti-parasitic drugs/chemicals
available in the market but always consult an
expert before their application in aquaculture

Common recommendations
• Lime (CaO) : 100 kg/ha, to enhance alkalinity
• Copper sulphate : Good for ectoparasite infestations,
but restricted use.
Dose: @ 50-100 mg/100 l (0.5 -1.0 ppm)
• Formalin : Restricted application
 150-250 ppm for 1 hour or
 20-25ml /100l for 30-60min.
 For prolonged: 2ml /100 l for 12-24 hours.
• Salt bath: 5% NaCl – 30 sec to 1 min bath treatment

• Cypermethrin (Clinar EC:10):
15ml/acre, 3 dose at 5 days interval
• Deltamethrin (Buox (1.25%) or
Ectodel (2.8%): (15ml/acre, 3 dose at
5 days interval)
• Invermectin power (1% w/w)
HITEK: mix 20-25g powder in
100kg feed, feed for 10 days
•Emamectin Benzoate: 5mg/100kg
biomass, feed for 10days
•Amitraz: Single dose
Insecticides for Animal Health care-
Not recommended but being used in aquaculture

• Increase water temperature to 30°C for 6 h daily for 3-5 d
• Daily bath treatment for 1 hr in 2-3% NaCl solution
• For aquarium fishes, add 1 ml of 1% Methylene blue solution
in 5 litres of aquarium water or Malachite green 0.1 ppm (10
mg/ 100 litre). Repeat the treatment for 1-2 days alternatively
till recovery.
• For pond treatment 0.5 ppm CuSO4 every week.
• Bath treatment with Formalin at 50-150 ppm for 60-90
minutes (with caution).
• For longer treatment use Formalin 15 ppm (1.5-2.0ml in 100
litre water) on alternate days at an interval of 6 days for pond
treatment (ensure water is well aerated).
Treatment for Ich:

Protozoan parasites: Nematodes
• Albendazole : 30g/ 100kg feed
• Fenbendazole/
• Flubendazole: 30g/ 100kg feed

• Most diseases arise from stressful conditions due to
poor husbandry and management practices.
• Improving farm management and sanitization : can
reduce the
incidence of disease occurrence
• Maintain optimum stocking density : avoid
overcrowding and excess handling.
• Farm Biosecurity:
• Quarantine all new stock, treat with antiseptics before
releasing into pond
• Proper disposal of dead/ diseased fish
Preventive and control measures:

CIFA Publications for Farmers

Take home message
Maintaining optimum water quality
with less stressful environment : Best
approach to disease management in
Freshwater aquaculture

Fish disease management guide

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