Prevalent Fish diseases in the carp polyculture system of Assam

The present study was undertaken to find out the incidence of different disease in the freshwater aquaculture system in three districts viz., Nagaon, Morigaon and Sonitpur of Assam. A total of 293 ponds of varying size were surveyed during the disease outbreak cases and fourteen different diseases were recorded with the highest intensity of ulcerative disease (28.01%) followed by red spot/haemorrhages (18.82%). The prevalence percentage recorded in the 3 districts on monthly basis were 18.84, 14.10, 2.70, 2.51, 2.93, 27.90, 3.27, 2.55, 2.14, 1.54, 1.62, 1.99, 5.60 and 2.25 per cent for red spot/haemorrhage, tail rot/fin rot, dropsy, popeye, gill rot, ulceration, scale erosion, anal protrusion, pinhead, lordosis/ scoliosis, argulosis, protozoan infection, cotton wool disease and ventral reddening, respectively. Month-wise prevalence of disease recorded in the district during study revealed that highest incidence of disease was recorded in the month of January (24.93%) followed by December (23.02%) and February (18.39%). Species wise prevalence of disease revealed that Mrigal was the most susceptible species with incidence of 54.44% followed by Catla (43.33%), Rohu (41.11%), Silver carp (38.89%) Puntius (33.33%), Common carp (28.89%), Gonius (27.78%), Bata (26.67%), Reba (19.99%), both Grass carp and L. calbasu (13.33%). The analysis of variance (ANOVA) revealed that there was marginal significant difference in districts with respect to diseases occurrence (P=0.051) which indicated an almost uniform pattern of incidence of diseases. However, the affected species of fishes were highly significant (p<0.01) from each other.