Fish Diseases
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Fishes are aquatic
organisms where they encounter various infectious agents such as bacteria,
virus, fungi and sometimes parasitic organisms. Healthy fishes cultured in
ideal aquatic parameters generally donot developed diseases. But sometimes
those pathogens infact the fishes, thus affecting the productivity of cultured
form ( the fish production)
It is important to monitor the cultured fish
in routin basis. Proper examination of fishes should be done if they developed.
●
Unusual movement or
swimming.
●
Show abnormal growth.
●
Complete or partial
discoloration of body.
●
Lost of scale.
●
Rotting or infection
in any part of body including fins.
●
Damage or
Discoloration of gills.
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Development of fill
like covering in the skin.
●
Excess slime
secretion.
Fishes diseases can be
divided on the basis of causative pathogen. The different types of fish
Diseases are described below-
A) Bactericidal Disease:-
Different types of bacteria can infect fishes & produced diseases.
a) Tail and Fin Rot
Disease:- This diseases are
caused by
Pathogen:-Aeromonas,
Pseudomonads, Mycobacterium and vibrio species (spp)
Symptom and Damage:- Initial damage in the
fin or tail occurs due to mechanical reasons where the bacteria infect a
whitish line or spot developes.
b) Droapsy:- It is caused by
Pathogen:- Aeromonas punctata &
Viral agent.
Symptom and Damage:- Accumulation of liquid
occurs in the belly of the fish, liver and kidney are affected at later period.
Ulceration of skin and lose of Scale may occur.
c) Eye Disease:-
Pathogen:- Aeromonas sp.
Symptom & Damage:- Initially the cornea
of the eye become reddish which turns opaque gradually. The eye ball also
degenerate.
d) Columneris Disease:-
Pathogen:- Flexibacter columneris.
Symptom & Damage:- Discoloration of body
occurs followed by mile ulceration.
e) Ulcer Disease:-
Pathogen:- Haemophillus piscicum.
Symptom & Damage:- Initially small
lesion developes followed by formation of open ulcer. Secondary fungal
infection may occur.
f) Furunculosis:-
Pathogen:- Aeromonas salmonicidea.
Symptom & Damage:- Formation of boil
containing blood & pus seen under the skin.
g) Gill Rot Disease:-
Pathogen:- Flexibacter columneris, Mixi
coccus.
Symptom & Damage:- Necrosis occurs in
the gill filament where mucus & debrish accumulate.
h) Vibriosis:-
Pathogen:- Vibrio spp.
Symptom & Damage:- Darkening of body,
ulceration and abdominal droapsy.
B. Fungal Disease:-
Various aquatic fungi
are capable of infecting fish species. Usually mechanical damage or ulcer
produced due to bacterial infection increases the chances of fungal disease.
A) Water Moule Disease or
Saprolegniasis:-
Pathogen:- Saprolegnia, Achlya.
Symptom & Damage:- At first the fungi
developed as a thin grayish or whitish layer on the wounded part of the body.
The hypi of the fungi inved the inner tissue as time passes or infection
increases. Water body rich in organic substance increases the chances of
Saprolegniasis in fishes.
B) Branchiomycosis:-
Pathogen:- Branchiomyces.
Symptom & Damage:- Decaying of gill
occurs resulting haemorage, slim secretion increases, eye & body colour
become pale.