Sustainable aquaculture: agro-ecological role of periphyton in ricefish farming

Aquaculture has a highly promising role in producing fish biomass and fulfilling nutrient requirement for the growing population on the Earth. Worldwide, there exists several substrate-based fish production practices of which Acadja, Athkotu, Samarah, Phum, Aji gnuii assonii, Xeng fishery are popular. These substrate-based fisheries reported higher fish productivity than conventional supplemental feed-based aquaculture. Herbivorous fish, in general, have natural tendency to graze on periphyton ensuring maximum accessibility to resources or acquire enhanced growth in a periphyton fed environment. In waterlogged rice fields with rice stem as substrate, common carp (Cyprinuscarpio L.) fishery has been a great success among agro-farmers of Apatani Plateau in north-eastern India. The practice achieves 30% more economic return per annum rice only cultivation. The practice is a best example of sustainable utilization of natural resources for fish production and also a low-cost aquaculture to support poor farmers with shallow, waterlogged resources. The ecology of the rice fields in Apatani Plateau disclosed high richness and diversity of plankton and periphyton in aquatic column. The physico-chemical nature of rice fields directly or indirectly affects the growth and dynamics of periphyton during rice-growing periods. On availability of such aquatic resources, the fish, Common carp, shifts planktivorous or detritivorous feeding habits to periphytophagous habit and attains considerable growth over the stocked period. The present review highlights the immense potentiality of fish culture to explore periphytic resources and need of extending ricefish research towards a sustainable form of aquaculture in rice fields.