World Journal of Fish and Marine Sciences 7 (4): 221-227, 2015 ISSN 2078-4589 © IDOSI Publications, 2015 DOI: 10.5829/idosi.wjfms.2015.7.4.9486 Corresponding Author: N.C. Roy, Department of Fish Biology and Genetics, Faculty of Fisheries, Sylhet Agricultural University, Sylhet-3100, Bangladesh. Tel. +88-01712-170930. 221 Optimization of Stocking Density of Mola (Amblypharyngodon mola) in Carp Polyculture under Low Cost Management for Rural Bangladesh N.C. Roy, M.A. Wahab, P.C. Ray and S.H. Thilsted 1 2 3 4 Department of Fish Biology and Genetics, 1 Sylhet Agricultural University, Sylhet, Bangladesh Department of Fisheries Management, 2 Bangladesh Agricultural University, Mymensingh, Bangladesh Department of Fisheries (DoF), Bangladesh 3 World Fish Centre, House 22B, Road 7, Block – F, Banani, Dhaka, Bangladesh 4 Abstract: The optimization of stocking density of mola (Amblypharyngodon mola) in the polyculture with Labeo rohita, Catla catla, Cirrhinus mrigala and Ctenopharyngodon idella was investigated. Four treatments were tried with seven replicates each. Only carp fingerlings were stocked in the treatment 1 (control) and carps with mola were present in treatments 2, 3 and 4. Three stocking densities of brood mola i.e. 100, 150 and 200 fish were tested in treatments 2, 3 and 4, respectively with stocking density of carps fixed at 43 fingerlings per 40 m pond. Most of the water quality parameters were not significant variations (P>0.05), however transparency 2 and chlorophyll-a varied significantly among the treatments. Although water quality parameters showed some variations among treatments but they do not have any definite trend in respect of different stocking densities of mola. Although individual growth of rohu showed variations among treatments, the fish productions in all treatments were not significantly different (P>0.05). Comparatively higher yield was recorded in treatment-1 (without mola), however carp with lowest density of mola (100 mola per 40 m pond area) was recommended for 2 nutritional, socioeconomic and production point of view. Key words: Optimization Stocking Density Mola Carp Polyculture Low Cost Management INTRODUCTION management measures in scientific fish culture practices. Aquaculture of Bangladesh is enriched with a the level of supplementary feeding required [4-5] and significant number of indigenous and exotic carp fishes. hence the intensity of inter- and intra-specific food Carps are basically the most important species to competitions in polyculture systems. In polyculture, both aquaculture in Bangladesh. In 2012-13, carp production native and exotic species are stocked together. Many of was estimated as 35% of the total fish production in the these species have been found antagonistic and feeding country [1]. There are at least 13 endemic and 8 competition to each other [6]. To overcome this situation, introduced species of carps, which are of interest to efforts have been made to develop a polyculture aquaculture in Bangladesh [2]. technique in rural Bangladesh with fast growing Polyculture of fish has been practised with the aim compatible species of carps and nutritionally rich mola that different species stocked in the ponds occupy [7-8]. It may exert synergistic effects in the polyculture different niches with their complementary feeding habits, and thus enhance fish production [9]. Mola is particularly utilizing all the natural food available in the ponds and important because of high content of vitamin-A than that thus increasing the total fish production [3]. Stocking of other edible fish species in Bangladesh [10-11]. A 100g density of fish is one of the key factors, deciding mola contains approximately 1,960 µg vitamin-A, 1,071 mg It affects the amount of natural food available per fish and