Periphyton based grow-out farming of Indian major carps with Labeo calbasu (Hamilton) and Puntius gonionotus (Bleeker) for better water quality and enhanced fish production

Abstract

Influence of two levels of periphytic substrate (bamboo mats) on water quality and growth performance of five carp species was studied in grow-out polyculture system in earthen ponds for six months. With similar fertilization and supplementary feeding in all ponds, stripped bamboo mats were provided to create 0, 10 and 20% substrate surface area for periphyton growth and designated as control, T-1 and T-2, respectively. The ponds were stocked with catla, rohu, mrigal, kalbasu and silver barb at equal species ratio and at combined density of 5000 fingerlings ha−1. Provision of periphytic substrates ensured prevalence of better water quality in terms of minimizing fluctuation of water parameters and increasing plankton availability in treatments, besides additional availability of periphytic biomass for feeding. Increased substrate area in T-2 caused more periphyton availability and less grazing pressure than T-1, but no marked influence on the plankton density was observed. The overall treatment survival, growth, SGR and net fish yield significantly increased with provision of substrate. Among the species, only rohu and kalbasu recorded significant increase in their growth in treatments than the control. But no significant growth difference of these species between T-1 and T-2 indicated 10% additional substrate area (in T-2 over T-1) was not enough to cause a significant improvement in their weights. However, the higher growth trends in rohu, silver barb and kalbasu with increased substrate area suggested further need to explore the possibility of increasing yield with more substrate, subjected to consideration of economic feasibility.