Growth performance of major carps in polyculture system at low (500/acre) and medium (750/acre) stocking densities

The present experiment was conducted to access the effect of different stocking densities in the growth performance of major carps under the influence of artificial diet (maize gluten). After preliminary preparation, these ponds' were stocked with Labeo rohita, Catla catla and Cirrhinus mrigala in a ratio of 30, 40 and 30% respectively. In pond 1, 19 Labeo rohita Catla catla and 19 Cirrhinus mrigala were already stocked. This stocking was done -at the rate of 500 major carps/acre. On the same pattern 27 Labeo rohita, 38 Catla catla and 27 Cirrhinus mrigala were stocked in pond 2. This stocking was done at the rate of 750 major carps/acre. Artificial feed (maize gluten) was given at the rate of 2% o of fish body weight daily for six months. The growth parameters, viz. increase in body weights, total lengths and fork lengths of fish were monitored on fortnightly basis. About 25% fish were netted out randomly from both ponds using; nylon drag net and their growth parameters were measured and recorded. Water samples were taken (from both pond 1 and pond 2 separately) on fortnightly basis and were analyzed for physico- chemical characteristics. The maximum weight gain 134, 34 and 76 gm were recorded in pond 1 in which stocking density was done at the rate of 500 major carps per acre during month of April. In pond 2, the maximum. weight gain 121, 52 and 44 gm were noted in which stocking density was at, the rate of 750 major carps per acre. Maximum gain in total length was noted as 1.5 cm fog- pond 1 and pond 2 during the months of March and April. Gain in total length of fish was non- significant. Maximum increase in fork length was observed as 1.3; 1.0 and 1.5 cm in pond l and 1.5, 1.5 and 1.0 cm in pond 2, Planktonic biomass was negatively and non-significantly correlated with water temperature in pond 2 and positively and non-significantly correlated in pond 1. The inter-pond differences of physico-chemical parameters were non- significant, except for carbonates.