Inclusion of Monosex Tilapia (Oreochromis niloticus) with Freshwater Prawn (Macrobrachium rosenbergii) in Polyculture Systems in the Ponds of Coastal Region: Impact of Stocking Density of Tilapia on Production and Profitability

Experiment was carried out to ascertain the impact of stocking density of monosex tilapia (Oreochromis niloticus) on production and profitability in freshwater prawn (Macrobrachium rosenbergii) farming system over a period of 150 days at farmers’ shrimp ponds, Madrasha village, Bamorta union, Bagerhat district. There were three treatments viz. T1, T2 and T3 with tilapia of 10,000, 15,000 and 20,000/ha, respectively and each having three replicates. Density of prawn at 20,000/ha was maintained in all the treatments. Ponds were stocked with monosex tilapia and all male prawn juvenile. On average, 25 genera of phytoplankton and 6 genera of zooplankton were identified from pond water. Water quality parameters were within suitable ranges for tilapia and prawn in all the treatments. Mean weight of tilapia decreased significantly (p<0.05) with increasing stocking density but survival rate did not differ significantly. Higher production of prawn was obtained in T1 (950.4 kg/ha) followed by T2 (923.0 kg/ha) and T3 (805.2 kg/ha). On the contrary, production of tilapia was significantly higher in T3 (1,686.60 kg/ha) and T2 (1,587.60 kg/ha) than in T1 (1,310.0 kg/ha). However, the overall total production of tilapia and prawn was significantly (p<0.05) higher in T2(2,510.60 kg/ha) and T3 (2,491.80 kg/ha) compared to T1 (2,260.40 kg/ha). Higher profit was also found in T2(BDT 238,923.00/ha) followed by T1 (BDT 222,557.00/ha) and T3 (147,819.00/ha). Therefore, the results of the study implied that inclusion of tilapia at a density at 15,000/ha enhanced the total production and contributed greatly to earn higher profit.