GROWTH AND PRODUCTION OF CARPS AND SIS IN PERIPHYTON ENHANCED SYSTEM
Role of small indigenous fish species (SIS) has been recognized for improving family nutrition in small-scale household aquaculture. An experiment was conducted at Agriculture and Forestry University (AFU), Chitwan, Nepal to compare fish production between carp-SIS polyculture and periphyton enhanced carp-SIS polyculture in order to develop a cost effective means to increase fish production. The experimental period was of 210 days from 24 August 2014 to 28 March 2015. The experiment included four treatments, T1 (Carp+100% Supplemental feed), T2 (Carp+SIS+100% Supplemental feed), T3 (Carp+SIS+50% Supplemental feed + Bamboo substrate at the rate of 1 % of pond surface area) and T4 (Carp+SIS+Bamboo substrate) each with three replicates. Silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), rohu (Labeo rohita) and naini (Cirrhina mrigala) were stocked at a ratio of 4:1:4:3:5 at rate of 15,000 fish/ha whereas two SIS, dedhuwa (Esomus danricus) and pothi (Puntius sophore) were stocked at a ratio of 1:1 at density of 50,000 fish/ha. Carps were fed with freshly made dough of mustard oil cake and rice bran (1:1) at 5% of body weight per day whereas Grass carp was fed with grass at 50% of body weight per day. Growth and yield of common carp was significantly? higher in T3 than all other treatments indicating both periphyton and supplementary feed at a reduced rate produced the best growth. Growth and production of grass carp was higher in ponds without substrate. Carp yield and combined NFY was higher in T3 due to the higher survival and growth rate of carp caused by periphyton and supplementary feed. Production of SIS was lower in substrate ponds. Gross margin was highest in T3, intermediate in T4 and lowest in T2. Based on fish production and profit, supplemental feeding at 50% combined with periphyton enhancement was best among treatments.