The aim of the present study was to investigate the fungal infection in fishes of Upputeru Creek of Kolleru Lake, Andhra Pradesh and the percentage of infection of various species of fishes. A total number of 1400 fishes were screened and fungal infected fish samples were brought to laboratory in sterilized plastic bags and kept in glass aquaria to observe the symptoms of infected fishes. Identification of various species of fungus was done on the basis of their vegetative and reproductive characters and standard keys described by various workers. Experimental infection trails were conducted to know the pathogenic nature of the fungi. Out of 1400 fishes examined, only 287 fishes were found to be infected with fungus. Eight species of fish viz., Catla catla, Labeo rohita, Channa punctatus, Channa striatus, Clarias batrachus, Mastacembalus armatus, Mystus cavasius and Mystus seenghala were found infected. A total of forty one isolates of fungi were recovered from the diseased fishes, which belongs to 8 genera and 14 species. Among all the eight genera, Achlya and Saprolegnia are found to be highly virulent. In case of monthly percentage of infection, the maximum percentage of infection was recorded in December, 2013 (23.2%) followed by January, 2014 (16.8%) and February, 2014 (15.3%) and minimum infection (9.2%) was reported in the month of October, 2013. In case of fish species, the maximum infection was observed in C. batrachus (25%) while minimum was noticed in C. catla (4%). Results of experimental infection trails indicate that Saprolegnia parasitica and Achlya sp are highly virulent in nature.

Keywords: Oomycetes, pathogenicity, symptoms, fishes.