Outbreak of Bacterial Haemorrhagic Septicaemia in Fresh Water Carps in Thanjavur Region of Tamil Nadu

In a private fresh water pond of one acre size, 3900 numbers of carps consisting of Catla (Catla catla), Rohu (Labeo rohita), Grass carps (Ctenopharyngodon idella), Mrigal (Cirrhinus mriqala)) and Common carp (Cyprinus carpio) were cultured at Orathanadu, Thanjavur, the aquaculture belt of Tamilnadu. The bacterial haemorrhagic septicaemia disease outbreak due to Aeromonas hydrophila in a fresh water carps pond was investigated in the year 2011. The clinical signs included anorexia, slow movement in water surface, chronic rubbing of body due to irritation, 16% mortality and 100% morbidity. Bacteriological examination of moribund fish and traditional biochemical methods were used for identification of A. hydrophila. The gross and hisopathological changes were studied. The vascular changes such as congestion and hemorrhage in the outside surface of the affected fish were the main gross lesion. Petechial and ecchymotic haemorrhages, erosions and ulcers were found in the skin. The vascular changes such as congestion and haemorrhages were recorded in the mouths, eyes, opercula and the base of fins and around the anus. The blood tinched serous fluid was recorded in the abdomen. The vital organs showed generalized congestion and enlargement with petechial and ecchymotic haemorrhages. The histopathological changes are characterized by generalised haemosiderine pigment deposition in all vital organs. In addition, vacuolar degeneration and necrosis in the dermis and subcutis, congestion and haemohhages with serous exudation in gill-lamellae, acute haemorrhagic myocarditis, cloudy swelling to hydropic degeneration with multifocal necrosis of liver, acute haemorrhagic enteritis and acute haemorrhagic nephritis were observed.The moribund fishes in the farm was treated with tetracycline and Curcumin longa.