Growth performance of major carps in polyculture system at medium (750/acre) and average (1000/acre) stocking densities

The present experiment was under taken to assess the effect of stocking density on the growth performance of major carps under the influence of artificial diet (Maize gluten). This experiment was conducted by using two earthen ponds each having dimensions of 33 x 16 x 1.5 m located at Fisheries Research Farms, University of Agriculture, Faisalabad. 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, 27 Labeo rohita, 38 Catla catla and 27 Cirrhinus mrigala were stocked. This stocking was done at rate of 750 major carps, per acre. On the same pattern Labeo rohita, 50 Catla catla 38 Cirrhinus mrigala were stocked in Pond 2. This stocking was done at the rate of 1000 major carps per acre. At the time of stocking average heady weights of Labeo rohita, Catla catla and Cirrhinus mrigala were 108 g, 180 gm and 170 gm respectively in Pond 1. Similarly in pond 2 the average body weights of major carps were 90 gm, 125 gm and 50 gm respectively. Average total lengths of major carps were 20 cm, 22 cm and 18 cm respectively in Pond 1. While in pond the average total lengths of major carps were 22 cm, 20 cm and 16 cm respectively. Artificial feed (Maize gluten) was given at the rate of 2% of fish body daily for 6 months. Ammonium Nitrate was added at the rate of rate 0.2 % of nitrogen of fish body weight daily. About 25% fishes were netted out from all the ponds fortnightly, to monitor the growth performance viz. body weight and total length. After recording the data fish were released back into their respective ponds. Water from all the ponds was analyzed, length for its physico-chemical characteristics. Based on the above experimental conditions the following conclusions were drawn. The maximum weight gain 59.8 gm, 45 gm, and 54.3 gm were recorded in pond 1, in which stocking density was done at the rate of 50 major carps per acre during the month of July. In Pond 2, the maximum weight gain 55.3 gm, 44.6 gm and 21.3 gm were noted in which stocking density was done at the rate of 1000 major carps per acre. The final harvesting of fishes in two treated ponds showed that maximum fish production was in pond 1 followed by pond. Maximum weight gain was noted during the months of July and August. Increase in body weight and total length was positively and significantly correlated with the increase in temperature. Water temperature was negatively and significantly correlated with dissolved oxygen. The inter-pond differences of physico-chemical parameters were non-significant.