Necessity of Dietary Mineral Supplements for the Growth of Freshwater Fish Cyprinus carpio and Heteropneustes fossilis

Thirty day feeding trials were conducted in 400-liter outdoor cement tanks separately for Cyprinus carpio and Heteropneustes fossilis to determine if mineral supplement is necessary for the growth of these freshwater fishes. Each of the species was reared under three dietary conditions: a basal diet with 31.5 % crude protein (T1), the basal diet containing 2% mineral supplement (T2) and the basal diet with an exogenous supply of live plankton at 5 ml concentrated suspension (containing about 800-1220 zooplankton) six days a week (T3). Both species showed a significant reduction in growth if the basal diet (T1) was not supplemented by minerals either as mineral mixture (T2) or through exogenous supply of plankton (T3). Deficiency of Co in the basal diet and in the test medium was found to be the reason for poor growth.