Isolation of pathogenic fungi from the major cultivated coldwater fish species and their environment in the kumaon region of Uttrakhand

An attempt has been made to isolate the pathogenic fungus from water, body tissue of cold water fish. The hemp seed culture was applied to obtain the fungal colonies and bacteria free pure isolate was obtained by repeated subcultures, using SDA (Sabouraud Dextrose Agar) under aseptic condition and allowed to incubate at 18–20°C for 48 hours. Fungal infection was more prominent in the ponds of stagnant water than the running water raceways. The inferior water quality of the stagnant fish ponds supports the virulence of the fungus spores. The muscles of the rainbow trout, fins and gills of the carp were susceptible for the infection. Intensity of the infection in cold water fish species increases with the downfall of the water temperature. The pathogenic fungi in the present study was identified as Saprolegnia parasitica, Saprolegnia diclina and S. ferax with cotton like appearance, elongated zoosporangia and pear shaped primary sporangium.