Periphyton-based pond polyculture system: a bioeconomic comparison of on-farm and on-station trials

A bioeconomic study of periphyton-based aquaculture in Bangladesh was carried out through comparison of on-farm and on-station trials. Five treatments, three on-farm and two on-station, each with four replications, were tried in a completely randomized design: on-farm control without substrate or feed (control), on-farm bamboo substrate only (treatment B-farm), on-farm substrate plus feed (BF-farm), on-station substrate only (B-station) and on-station substrate plus feed (BF-station). All ponds were stocked with three native major carps, rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) at a ratio of 60:40:15 and a stocking density of 11,500 juveniles ha-1. All ponds were fertilized fortnightly with urea and triple super phosphate (TSP) at the same rate of 50 kg ha-1. In substrate treatments, ponds were provided with bamboo poles as periphyton substrates. In fed treatments, rice bran and mustard oil cake (ratio 2:1 by weight) were applied. The environmental conditions of on-station ponds were better than on-farm ponds. Under on-farm condition, substrate plus feed (BF-farm) and substrate only (B-farm), respectively, resulted in 59% and 28% higher production over control. Under on-station condition, supplemental feed did not contribute significantly to the total fish production. However, on-station trial resulted in 77% higher combined net yield than on-farm trial. The cost–benefit analysis indicated that well-managed periphyton-based aquaculture practices might be a profitable business. The sustainability issues of this novel technology needs to be carefully assessed during the design and planning of aquacultural developmental efforts