Fungal Diseases in Fishes

a. Saprolegniasis disease:

• This disease is also called as “Cotton Wool” or “Water Mould Disease”.
• This disease is caused by Saprolegnia parasitica.
• It is the most common fungus affecting fishes, especially major carps.
• The fry and fingerlings, when transported over long distances get bruises on the body, and unless properly disinfected, become sites of infection, resulting in large scale mortality.
• Whenever fish get injuries the fungal infection may occur.
• The infected fish becomes weak and lethargic or exfoliation of the skin followed by haemorrhage, exposure of jaw bones, blindness and inflammation of liver and intestine.
• This can be treated with 1-3 ppm malachite green for one hour or 1:500 formalin for 15 minutes.

b. Branchiomycosis disease:

• This is also called as “Gill Rot”.
• This disease is caused by Byanchiomyces demigrans and B. sanguinis.
• It is reported to be common on cultivated fishes in ponds having abundant decaying organic matter.
• The tubules of fungus grow into the respiratory epithelium of the gills, causing inflammation and damage to their blood vessels.
• The blood supply is stopped to the infected area. As a result of which it becomes necrotic.
• It can be controlled with 5% common salt for 5-10 minutes.

c. Ichthyophonosis disease:

• It is also known as “Reeling Disease”.
• It is characterized by swinging movement of the infected fish.
• It is caused by Ichthyophonus hoferi. It enters into the host along with the food. The spores spread to the various organs and in severe cases spread out to the skin which may rupture and become ulcerative at several places.
• It is extremely difficult to control this disease. The infected fishes are isolated from the stock and kept for treatment in separate ponds.
• Medicines like sulfamethanis, terramycin, erythromycin and calomel are useful to treat the infected fish.