Performance evaluation of rice-fish integration system in rainfed medium land ecosystem

This study was carried out for three successive years during 1999-2001 to evaluate growth and yield performance of fish, prawn and paddy under rice-fish integration system in tainted medium land ecosystem. Irrespective of stocking density, faster growth rate was recorded for Catla catla followed by Cyprinus carpio, Cirrhinus mrigala, Labeo rohita and Macrobrachium rosenbergii. C. carpio and C. mrigala performed better growth rate against that of L. rohita probably due to the fact that being bottom dwellers, C. carpio and C. mrigala are more tolerant to fluctuation of oxygen concentration. Productivity of fish and prawn was, however, higher (p < 0.05) in refuges with 10-cm weir height plots, irrespective of stocking density, while overall yield performance was good at stocking density of 25,000 ha(-1). It was observed that, even with supplemental feeding, with increase in stocking density, biomass yield increased up to an optimum and then decreased. An average minimum and maximum yield of 906.6-1282.3 kg ha(-1) of fish and prawn has been achieved, which was much higher than the earlier recorded productivity in a season under rice-fish integration system. Highest grain yield was recorded at 15-cm weir height plot (3629 kg ha(-1)), probably contributed by higher number of panicles per square meter (235.5) and number of filled grains per panicle (121.7). Percentage increase in rice yield under rice-fish integration system was 7.9-8.6% against control, where paddy was cultivated without integration of fish and prawn probably due to better aeration of water, greater tillering effect and additional supply of fertilizer in form of leftover feed and fish excreta. Irrespective of stocking density, the overall rice equivalent yield (REY) of the system was high (4.22-4.55 tons ha(-1)) at 12.5-cm weir height plots-cum-refuge, without using any pesticide, herbicide, etc. (C) 2004 Elsevier B.V. All rights reserved.