Effects of feeding rates on production of common carp and water quality in paddy-cum-fish culture

The effects of artificial feeding on production of common carp (Cyprinus carpio) and water quality in paddy-cum-fish culture were studied for 90 days. Paddy fields of 40 m2 were stocked with 24 fingerlings (25 to 30 g) 15 days after transplanting the paddy seedlings. The fish were fed a mixture of rice bran and mustard oil cake (1:1) at rates of 2, 4 and 6% total body weight. The growth of individual fish and fish yield increased with increasing feeding rates, as did concentrations of nitrite, nitrate, chemical oxygen demand, and particulate organic matter. The concentration of dissolved oxygen decreased. Economic interpretation indicated a feeding rate of 8.8% of the total body weights of the fish, calculated on the Mitscherlich model. The values for pond conversion and water quality indicated that feeding beyond 4% was wasteful, and accumulation of the feed caused deterioration in water quality.