Effect of different stocking ratios on the production and survival of indigenous carps and pangas (Pangasius hypophthalmus) in a pond system

The experiment was conducted to find out the appropriate combination of indigenous carps and Thai pangas (Pangasius hypophthalmus) for polyculture in respect to growth, survival and production in different farmers ponds under semi intensive rearing system. There were three treatments (T1, T2 and T3) each with four replications. The average size of the ponds varied from 0.8 acre to 1.0 acre with an average depth of water 1.2 m to 1.5 m. Four species were selected for the experiment and stocked the density of 100/decimal with different ratio of carps and pangas. Among the carps only three Indian major carps viz. rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) were selected. The initial stocking weight of rohu, catla, mrigal and pangas was 3.14, 4.20, 3.60 and 6.73 g, respectively. The stocking ratio of rohu, catla, mrigal and pangas were 35:17.5:17.5:30, 30:15:15:40 and 25:12.5:12.5:50 in three treatments. Supplemental feed containing 27.96% crude protein was provided only for pangas at the rate of 8% of their body weight. Feed was supplied in the form of dough twice a day and no feeding tray was used. The average final weight gain of pangas in all treatments was higher than any other species. The average highest final weight gain of pangas (340.10g) was recorded in T2 and lowest in T3 (318.19 g). On the other hand, average highest final weight gain of rohu, catla, and mrigal were found in T1 (250.28, 324.19 and 290.70 g) and lowest in T3 (200.37, 271.59 and 226.53 g). The mean survival rate of pangas varied from 93.36% to 95.17% and for carps 89.00% to 91.07%. The significantly highest total production of fishes was 2627.48 kg/acre/3 months recorded in T1 which was followed by T2 (2553.77 kg/acre/3 months) and T3 (2448.41 kg/acre/3 months) respectively. The FCR values were 1.23, 1.26 and 1.20 for the T1, T2 and T3, respectively. After the economic analysis it has been found the higher net return was (96,337.75 TK/acre/3 months) obtained in T1. So it can be concluded that species T1 (rohu: catla: mrigal: pangas = 35:17.5:17.5:30) is the best species combination for carp and pangas polyculture.