An unusually large sized long (26.0 cm) whiskered catfish Mystus gulio was collected from Visakhapatnam harbour having an abnormally bloated abdomen and emaciated tail. There were no external lesions, but the discoloured liver was hyperplastic. Microscopic, examination of liver tissue revealed polymorphic liver cells with nuclear and nucleolar enlargements, sporadic binucleate and multinucleate cells and PAS and BPB positive intra cytoplasmic inclusions. Derangement of kidney tubules and appearance of melano macrophages were observed in kidney and gonads. High concentrations of heavy metals and hydrocarbons in the harbour waters seem to have affected the fish.