Abstract: Parasitation of isopod, Joryma brachysoma was observed in Ilisha melastoma collected from fish catches off Parangipettai coastal environment, southeast coast of India. In parasitized fish skin lesions were observed in the gill and body surface due to the attachment of parasite. In the lesioned spots a heavy load of Total Heterotrophic Bacteria was observed. Vibrio parahaemolyticus and V. anguillarum were abundant at the site of parasitic lesion. The microbial load in the parasitized fish was significantly higher. Cenocytic fungal pathogens were also isolated from the lesioned sites.