Effects of including catla and tilapia in a freshwater prawn-mola polyculture in a rotational rice-fish culture systems

An on-farm trial was carried out from February to June 2006 to evaluate the growth and production performance of catla (Catla catla) and tilapia (Oreochromis niloticus) with freshwater prawn (Macrobrachium rosenbergii) and mola (Amblypharyngodon mola) in farmer's rice fields. In all treatments, 20 000 mola ha−1 and 20 000 prawn ha−1 were stocked. Besides, stocking included 2500 catla ha−1 in treatment-I, 2500 tilapia ha−1 in treatment-II and catla and tilapia at 1250 ha−1 each in treatment-III . Prawns were fed in the evening with pellets at a feeding rate of 3–8% body weight (initially 8% and gradually decreased to 3%). Catla and tilapia were fed in the morning with a paste of mustard oil cake and rice bran at a feeding rate of 3% body weight. Significantly higher combined production of fish and prawn observed was 2142 kg ha−1 in treatment-I. The benefit:cost ratio was found to be significantly higher in treatment-I than in treatment-II and there were no differences between treatments I and III. From the production and economic point of view, treatment-I was found to be the best proposition for the rotational rice–fish culture systems.