Use of artificial substrates to enhance production of freshwater herbivorous fish in pond culture

Two trials were concrete tanks to assess the potential of using artificial substrates to enhance fish production in ponds. Three substrate types were tested: bamboo poles, PVC pipes and sugarcane bagasse bundles, In one trial , periphyton was grown on the substrates in the absence of fish. In the sec ond trial, masheer (Tol khudree Sykes) fingerlings were stocked at three de nsities, Results showed a significant effect of substrate type on fish grow th (P less than or equal to0.001) and on net fish production (P less than o r equal to0.05), with best growth in the tanks using the bamboo substrate. In the bagasse treatment, 100% fish mortality occurred, Highest extrapolate d periphyton-based gross fish yield (i.e. without feed inputs) was 450 kg h a(-1) 90 d(-1) with PVC and 491 kg ha(-1) 90 d(-1) with bamboo substrate. T he best periphyton growth occurred on bamboo, followed by bagasse and PVC, Without fish, mean periphyton biomass during the culture period was 0.56-1. 20 mg cm(-2) on bamboo [ash-free dry matter (DM)I, against 0.09-0.36 mg cm( -2) on PVC and 0.20-0.59 mg cm(-2) on bagasse, No clear effect of fish dens ity or water depth on periphyton biomass could be seen. Only on bamboo, fis h density seemed to have a negative effect on periphyton ash-free dry matte r and a positive effect on pigment content (chlorophyll-a and phaeophytin), Periphyton from bamboo had a lower ash content (35-47% of DM) than from PV C (54-55% of DM) or bagasse (51-58% of DM), It is concluded that substrate type has a strong effect on periphyton productivity and composition, and on fish productivity. Good fish production was achieved without feed inputs. More research is needed to study the economic viability of periphyton-based systems in the context of Indian aquaculture.