Caused by various groups of aquatic fungi; primarily Saprolegnia, Achlya and Aphanaffects. All species and ages of freshwater and estuarine fishes. Effected fish develop white to brown cotton like growths on skin, fins, gills and dead eggs.
Branchiomycosis (Gill rot)
Caused by two species Branchiomyces sanguinis and B. demigrans. Primarily a problem in carp, rainbow and brown trout, and eels. Affected fish usually show respiratory distress.
Freshwater and saltwater species are effected mostly. White to yellow cauliflower-like growths on the skin, fins, and gills. Entry through epidermal abrasions
Mycobacterium species (Tuberculosis)
All species of fish are affected. Anorexia, vertebral deformities, exophthalmus, and loss of normal coloration, granulomas are often observed in various organs. Fish becoming infected by ingestion of bacterial contaminated feed or debris
(Furunculosis, Ulcerative disease of goldfish) Salmonids & other freshwater fishes can be affected. Septicemia with hemorrhage in the muscles and other sites. The major lesion is ulcerative dermatitis.
Signs of diseased fish
Symptoms of diseases differ according to its nature, but common signs are follows:
- Discoloration of body
- Rapid secretion of gray colored slime on the body
- Appearance of white, brown or black spots on the body
- Growth of fungus
- Irritation, due to which fish rubs its body against any fixed object, stones and plants
- Folding of fins and lingering either at the surface or bottom
- Increase in breathing frequency, rapid movement of operculum
- Whirling or tumbling movements
- Internal disease cause abdominal swelling, blood in excretions
- Fish population stops eating.
In combating fish diseases, the best thing is to take preventive measures. Mostly diseases are enhanced by poor environmental condition and improper management. Follow measures should be taken to obtain hygienic condition and healthy maintenance of fish ponds and tanks.
- Good pond water supply
- Excessive growth of plants must be prevented
- Pond and tanks must be dried at least once in two years
- Disease free fish should be selected for stocking
- Overcrowding should be avoided
- In the event of outbreak, dead or seriously infected fish must be destroyed
- Excessive and rough handling must be avoided
- Disinfection of ponds, tanks and aquaria is advisable before fish stocking