Diversity of Fungal infections and Histopathological preparations of some economically important Fresh Water Fishes in Bhadra Reservoir Project, Karnataka, INDIA

Abstract

Fungal infections are very serious diseases in culturable freshwater fishes. The present research work aimed to investigate the fungal infections in four economically important freshwater carps i.e. Catla catla, Labeo rohita, Cirrhinus mrigala and Cyprinus carpio which were collected from the Fish seed production unit at Bhadra Reservoir Project (BRP). The infected fishes were collected in polythene bags and brought for mycological study in the laboratory. The fungal strains were isolated using potato dextrose agar and Sabourd’s dextrose agar media. Out of 240 fishes, 168 (70%) infection have been recorded with six different fungal genera of Saprolegnia sp. (54.167%), Penicillium sp. (7.14%), Aspergillus sp. (14.285%), Trichoderma sp. (6.546%), Rhizopus sp. (4.167%) and Mucor sp. (13.695%). These fungi were frequently isolated and identified based on spore structure and morphological characteristics. The monthly variation and percentage of fungal infection in Catla catla was 35.10 %, Labeo rohita was 24.99%, Cirrhinus mrigala was 21.41% and Cyprinus carpio was 18.42%. Winter season (57.5%) and the rainy season (39%) was more favorable for the growth of Saprolegnia sp. than summer season (10%). Histopathological study was carried out to study the effect of Saprolegnia sp. on infected fish. Based on the results, Catla catla fishes were more susceptible to Saprolegnia sp. than other varieties of fishes.