Growth, Survival and Cost-benefit Analyses of Nutrient Rich Small Indigenous Species in Carp Polyculture System under Barind Area in Rajshahi District of Bangladesh

This study was conducted in Tanore upazila (sub district) of Rajshahi district, Bangladesh for a period of six months from July 2019 to December 2019. Investigation was carried into the economics of polyculture of Indian major carps with small indigenous fish species (SIS) Shing (H. fossilis), Magur (C. batrachus), and Pabda (O. pabda). The species composition was carps with shing (T1), carps with Magur (T2), carps with Pabda (T3) and only carps (T4). The economic feasibility of four different combinations was analyzed on the basis of the expenditure incurred and total return from sale price of fish in the local market. The net benefits per hectare from 6 months culture period for T1, T2, T3 and T4 were Bangladesh currency (Taka) as BDT. 635730.42, 805548.25, 580948.95 and 291489.07, respectively which largely reflected the gross fish production levels of 7680.42 ± 6.68, 8324.94 ± 16.64, 7581.13 ± 24.94 and 6344.55 ± 10.30 kg ha-1. However, carp polyculture with Magur (T2) provided highest benefit (BDT. 805548.25 ha-1), followed by carps-shing polyculture (BDT. 635730.42/ha-1), carps-Pabda polyculture (BDT. 580948.95 ha-1) and only carps (BDT. 291489.07 ha-1). BCR (Benefit Cost Ratio) was obtained highest in Carp-Magur polyculture, followed by carp-shing and carp-Pabda polyculture systems. So, Carp-Magur polyculture may be better as it has ensured better production of protein enriched SIS Magur and also economic point of view and this system is encouraging for rural people because they would get Magur regularly for consumption and carps as a cash crop.