There are many diseases of fish which can be troublesome to commercial producers as well as the recreational pond owner. Many disease outbreaks of captive fish stocks are associated with stressful conditions such as poor water quality, excessive crowding or inadequate nutrition.

1. Mr. Amit Bera
Aquaculture Consultant
beraamit03@gmail.com

2. What is Fish Health Management?
 Fish health management is a term used in aquaculture to describe management
practices which are designed to prevent fish disease.
 Once fish get sick it can be difficult to salvage them.
 Successful fish health management begins with prevention of disease rather than
treatment.
 Prevention of fish disease is accomplished through good water quality
management, nutrition, and sanitation.
 The fish is constantly bathed in potential pathogens, including bacteria, fungi, and
parasites.
 Daily observation of fish behavior and feeding activity allows early detection of
problems when they do occur so that a diagnosis can be made before the majority of
the population becomes sick.
 If treatment is indicated, it will be most successful if it is implemented early in
the course of the disease while the fish are still in good shape.

3. • Fish disease is a substantial source of monetary loss to aquaculturists.
• Production costs are increased by fish disease outbreaks because of the
investment lost in dead fish, cost of treatment, and decreased growth during
convalescence.
• Usually other circumstances must be present for active disease to develop in a
population.
• Management practices directed at limiting stress are likely to be most effective in
preventing disease outbreaks.
The Significance of Fish Disease

4. Relationship of Environment between Fish and Pathogens:
Presence of the fish pathogens will result in epizootics only if unfavorable
environmental conditions exist and the host defense mechanism has been
compromised.
If the
relationship is
balanced, good
health and
growth will
occur
If it is marginally
changed, a
chronic disease
problems and
reduced growth
will occur.
If it is
unsatisfactory,
poor growth and
overt disease will
result

5. Factors affecting on the Fish Health:

6. Some of the notable symptoms of healthy fish:
 The shape of the head of a healthy fish never seems bigger than the body.
 The body and the scales will be very bright.
 The gills are red in color and will have no spots or sores.
Shining
Natural
Color
Fins &
Tail
are intact
Never come
to the Edges
of the pond
Never Seen
on the
surface
of the Pond
No
Wounds
on the
Body
Takes
Feed
in Time

7. Loss of
Natural Color
Fins and Tail
Necrotic
Wounds
on the Body
Eyes Enlarged
and
Exophthalmic
Loss of
Stability &
Homeostasis
Gills loose natural
Red color –Pale in
Color or Necrotic
Fish Comes to
Surface & Swims
slowly very often
Heavy Mucous
on the
Body & Gills
Distended
Abdomen – Colon
filled with Fluid
Breaths
with Mouth
Edging
Loss of
Appetite

8. The tendency of fish diseases is more or less depending on the season. We can divide
the diseases of fish into the following few parts –
Fungal Disease
EUS
Nutritional Deficiency Problems
Environmental Related Problems
Protozoan Parasites
Helminth Parasite
Crustacean Parasite
At present fish farmers are facing all kinds of fish diseases. In general, I will discuss
all those fish diseases here.
Bacterial Disease
Parasitic Disease

9. 1. Fungal Disease
If there is any injury on the body of the fish during transport or during the growth
and health examination of the fish, at the site of the injury, the fungus spreads its
nest.
Saprolegniasis: Water Mold, Skin Fungus, Cotton Wool Disease etc.
Causative Agent: Saprolegnia parasitica
(Cotton Wool Disease) (Gill Rot)
Saprolegnia parasitica
Branchiomyces sanguinis

10. Symptoms of Saprolegniasis:-
1. Fish fungus appears as grey/white patches on the skin or gills of host fish or eggs
that resemble tufts of cotton-wool. At a later stage they may become brown or
green as they trap sediment or green algae.
2. Microscopic examination shows broad, non-septate (no dividing cell walls) hyphae
of varying diameters.
3. Gills necrotic.
4. Brushing against solid objects.
5. In severe cases Saprolegnia may actually penetrate into the
muscle tissue.
6. Fishes become lethargic, listless and less responsive to external
stimuli

11. Saprolegnia

12. Cotton wool disease

13. Treatment:-
 Dry the pond and remove the silt.
 Reduce the stocking density.
 Reduce Organic Matter.
 Apply Formalin @ 1lt + 100 gm of Malachite Green per Acre.
 Mix Salt @ 50-60 kg per ton of Feed for 5-6 days.

14. Branchiomysis: Gill Rot
Causative Agent: Branchiomyces sanguinis
Symptoms of Saprolegniasis:-
1. The gills lose their normal red colour and turn yellowish brown.
2. The affected gill filaments die, decompose, and fall off.
3. The fish become lethargic, gasp for air, breath with difficulty, and finally
suffocate.

15. Treatment:-
 Dry the pond and remove the silt.
 Reduce the stocking density.
 Reduce Organic Matter.
 Liming the pond @ 50kg/ha.
 Apply Formalin @ 1lt + 100 gm of Malachite Green per Acre.
 Mix Salt @ 50-60 kg per ton of Feed for 5-6 days.
 Bath treatment of the affected fish with Sodium Chloride @ 3- 5%

16. 2. Bacterial Disease
Pseudomonas sp. Aeromonas sp. Flexibacter columnare
Tail Rot & Fin Rot Hemorrhagic Septicemia
(Abdominal Dropsy)
Columnaris
(Saddle Back Disease)

17. Tail Rot & Fin Rot:
Causative Agent: Pseudomonas sp., Aeromonas sp.
Symptoms:-
1. Tail & Fins Necrotic.
2. Fish become ugly due to total necrosis of fins & tail.
3. Muscles exposed.

18. Tail & Fin Rot

19. Treatment:-
 Apply BKC @ 1 lt. per Acre.
 Mix OTC @ 100 gm per ton of Fish per Day for 6-7 days.
 Reduce stocking Density.
 Better management of Water Quality.

20. Hemorrhagic Septicemia (Infectious abdominal Dropsy) :
Causative Agent: Aeromonas sp.
Symptoms:-
1. Commonly Called as Red Diseases (sores on the body).
2. Dropsy.
3. Colon, Intestine, Anus become reddish in color.
4. Eyes protruded.
5. Pus comes out through anus.
6. Common in summer season.

21. Abdominal Dropsy
Red Disease

22. Treatment:-
 Application of 5 ppm Potassium permanganate.
 Manage Water quality.
 Mix 100 mg teramycine tablet/kg feed of Fish for 5-6 days.
 Infected fish should removed from the pond.
When dropsy makes its appearance, any dead fish should be collected, and buried.
Those which have been ill are never put into hy-bernation together with healthy
fish. After the fish have been removed the tanks should be disinfected with quick
lime and are left dry throughout the winter period

23. Columnaris:
(Commonly called as Saddle Back Disease)
Causative Agent: Flexibacter columnare.
Symptoms:-
1. Initial stages exhibit small greyish patches over head, on the edges of the
scales and on the fins, although the gills and lateral sides of the body may
also be affected. A chararacteristic lesion produced by columnaris is a pale
white band encircling the body, often referred to as saddle back.
2. In the later stage the pathogen penetrates the epidermis and dermis and
forms red ulcerations in the musculature. The gill filaments disintegrating
and gill necrosis observed.
3. Mass mortality of Fish particularly Rohu fish.
4. Commonly noticed in winter season.

24. Columnaris

25. Treatment:-
 Reduce Stocking Density.
 Water Quality management.
 Pond bottom management.
Mix OTC @ 100 per Ton of Fish per day for 6-8 days.
Apply BKC @ 1 ltr. per Acre.
 Infected fish should removed from the pond.

26. 3. PARASITIC DISEASES
Protozoan Parasites Helminth Parasites
Crustacean Parasites

27. Protozoan Parasites
Protozoans constitute one of the most important group of animal parasites affecting
fish. Protozoans are one – celled organisms that consist of a cell nucleus enclosed by a
cell membrane. Many of them cause fatal disease if the fish are not treated in time
Icthyophthiriasis Trichodiniasis Myxosporidians
Ichthyopthirius multifilis Trichodina reticulata Myxobolus sp.
Icthyophthiriasis
(White spot disease or Ich) Trichodiniasis Myxosporidians

28. Icthyophthiriasis: Water Mold, Skin Fungus, Cotton Wool Disease etc.
Causative Agent: Ichthyopthirius multifilis
Symptoms:-
1. Heavy Mucous Secretion.
2. Gills Necrotic.
3. Looses natural color and stops Feeding.
4. Affected fishes show irritation, erratic movement and restlessness with
tendency to rub on the sides.
5. Minute white spots, nodular in form and in size are visible on the skin, fins and
gills.

29. Ichthyophthiriosis
Treatment:-
 Reduce Stocking Density.
 Apply Formalin @ 1 ltr. & 100 gm malachite Green per acre.

30. Myxosporidians:
Causative Agent: Myxobolus sp.
Symptoms:-
1. Lives in Alimentary canal & Gills.
2. Spores are spindle/ Oval shaped.
3. Cysts are commonly seen in Gills as white spots.
4. Each cyst contains lakhs of Spores.
5. Commonly noticed in winter season -causes respiratory problem.
6. Poor Growth.

31. Myxobolus-Cysts on Gills
Myxobolus- Spores
Treatment:-
 Reduce Stocking Density.
 Apply Formalin @ 1 ltr. & 100 gm malachite Green per acre.

33. Crustacean Parasites
Crustaceans are almost without exception aquatic animals which breath by means of
gills. The grater part of the crustaceans undergo a metamorphosis with frequently
includes a nullius stage. Sexual dimorphism is common among parasitic crustaceans.
Crustacean parasites are frequently found to infest fishes. Infestation of fishes in
confined water very often causes serious diseases outbreak.
Argulosis Lernaeosis
Argulus foliaceous Lernaea sp.
(Fish lice) (Anchor Worm)

34. Argulosis: (Fish lice) Causative Agent: Argulus foliaceous
Symptoms:-
1. The adult parasite is oval, flat, and transparent to whitish with two conspicuous
black spots. It attaches to the skin and fins of the fish via suckers and feeds on
blood.
2. It is visible moving freely on the surface of the host fish.
3. Affected fishes are restless with erratic swimming behavior.
4. Loss of appetite.
5. Attachment sites shows sign of ulceration.
6. In case of severe infection, growth retardation and sometimes mortality occur.
7. Flickering and Gliding of Fish.
8. Infested fish rub on submerged objects or bottom substrates in an attempt to
dislodge the parasite from their skin.
9. Heavy mucous on the body.

35. Fish Lice

36. Treatment:-
 Reduce Organic Matter.
 Apply Cypermethrin @ 100 ml per acre.
 Apply 1 – 2 ppm dichlorves (Nuvan).
*** Cypermethlin & dichlorves will kill the prawn & shrimps.
So pond having shrimp/prawn, application of cypermethlin & dichlorves is not
recommended.

37. Epizootic Ulcerative Syndrome (EUS)
 Mixed Infection of Bacteria, Fungus, Protozooans.
 Black & White fish are affected in winter season.
 Reddish & Grayish wounds are noticed on the Body.
 Mass mortality of Fish noticed Ulcer on the body

38. Treatment:-
 Apply Quicklime @ 50 kgs + 30 kgs salt per acre.
 Sulphadiazine application in feed @ 100mg/kg of feed.
 Mix OTC( 10 %) @100 Gms + Furazolidon @ (20%) @50 gm per
ton of Fish per day for 6-7 days.
 Application of CIFAX gives good result

39. Nutritional Deficiency Problems
Problem Symptoms Deficiency
Lordosis Wrinkle of body Vit. - C, A, P & Mg
Catract Fatty Layer in Retina Methionine, Vit.-A
Necrotic Fin & Tail Rot Lysine, Vit.-A & C
Fatty Liver High Fat in Liver Cholin, Stale feeds
Blood Spots Blood spots at Fin bases Riboflavin & Pantothenic acid

40. Lordosis
Cataract

42. Environmental Problems
High Nitrite:
1. > 01 ppm of Nitrite in the water Toxic to fishes - causes Respiratory problem.
2. Gills become Chocolate color.
Treatment:-
1. Water Exchange.
2. Apply Quicklime @ 30-40 Kgs + 40 kgs per acre.
3. Use Bio-remediators
Ammonia Toxicity
1. >0.1 Free ammonia is Toxic to Fish.
2. Fish Becomes lethargic.
3. Surfacing during early morning.
4. Stops Feeding.
5. Mass Mortality.
Treatment:-
 Water Exchange.
 Apply Zeolite @ 10-15 Kgs per Acre

44. Oxygen Deficiency
1. < 2 ppm of Oxygen is harmful to Fish.
2. Surfacing & Air Gulping during early morning.
3. Mass level Mortality.
4. Fish Color fades and become pale.
Treatment:-
1. Exchange with freshwater.
2. Apply Calcium Peroxide @ 500-600 Gms per acre.
3. Apply Hydrogen Peroxide @ 500-750 ml per acre.

45. Surfacing & Air Gulping of Fish

46. SOME USEFUL CHEMICALS AND MEDICINE
TO
CONTROL FISH DISEASES
Formalin
• Aqueous solution of 37 – 40% by weight of formaldehyde gas.
• It kills protozoan, fungal and helminthes parasites.
• Formalin is highly toxic to phytoplankton and oxygen depletion may occur in pond due
to algal death.
BKC (Benzalkonium Chloride)
• It is a compound of mixture of alkyl dimethyl benzyl ammonium chlorides.
• It has anti-bacterial and anti-fungal property
• This compound is available as 50% and 20% solution commercially.
• Dosage for treatment of pond water is 0.5 – 1.0 ppm for 50% solution and 1.0-2.0
ppm for 20% solution

47. Potassium Permanganate
• It is a strong oxidizing agent with good antimicrobial activity.
• It releases nascent oxygen while dissolving in water.
• The nascent oxygen destroys micro organisms as well as organic organic substances,
through its oxidizing action.
• Do not use Potassium permanganate frequently since the manganese metal and
manganese dioxide may settle on the gill surface of fish/prawn and interfere with their
respiration.
Malachite Green
• It is greenish crystal with metalic lusture. It is very soluble in water.
• The water solution appears as blue-green.
• It is very effective against fungal disease.
Acriflavine
• It is also known as 3,6-Diamino-10-methylacridinium chloride
• It is an antiseptic, protozoacide.

48. Zeolite
• It occurs naturally in sedimentary and volcanic rocks.
• Commercially it is found in the form of grayish-powder form.
• The cations in zeolite are mobile and capable of undergoing ion exchange.
Therefore zeolite act as a cation exchanger. It can selectively absorb NH4
+ in water
Oxytetra-cycline (OTC)
• It is a broad-spectrum antibiotic against gram-positive and gram-negative bacteria.
• It is also effective against some protozoan infections.
• It inhibits the synthesis of bacterial proteins. Thus the growth of bacteria is
controlled.
• It is readily absorbed from the intestinal tract and can get into bacterial cell
quickly. Hence it is more effective when given orally.