RESUMEN
Fish serves as food for mankind. Flesh of fish is a perishable commodity. A study was taken to ascertain the pathogenicity of Aeromonas hydrophila; Pseudomonas aeruginosa and Vibrio parahaemolylicus on Indian major carps Catla catla and Labeo rohita. Among the three bacteria used, Aeromonas hydrophila was more pathogenic followed by Vibrio parahaemolyticus and Pseudomonas aeruginosa. Among the carps tested Catla catla was found to be more susceptible than Lobeo rohita. The major biochemical components such as the protein, carbohydrate and lipid levels showed significant variation between the control and infected groups [p<0.05] Morphological chances like yellow coloured abdomen, haemorrhage on the head region, swelling of the abdomen, accumulation of fluid in the abdomen and necrosis of the internal organs were observed in the Aeromonas hydrophila and Vibrio parahaemolyticus infected carps