Over-wintering growth of Macrobrachium rosenbergii (de Man) with carp polyculture in Bangladesh fed formulated diets

An experiment was conducted from December 2003 to April 2004 to observe the over‐wintering growth of freshwater prawn, Macrobrachium rosenbergii, with catla, Catla catla and rohu, Labeo rohita in polyculture using formulated diets. The study was conducted in eight experimental ponds, each 80 m². Three experimental diets containing 30% protein were prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses (binder), and assigned to treatments T₁, T₂ and T₃ respectively. A commercial diet from Saudi‐Bangla Fish Feed was assigned to T₄ (reference diet). Each treatment had two replicate ponds. Juvenile prawns and catla and rohu fingerlings (initial weight 1.60±0.10, 30.0±1.2 and 25.0±1.1 g respectively) were stocked at a ratio of 2:1:1 (prawn:catla:rohu). A total of 160 prawn and fish (20 000 ha^?1) were stocked in each pond. Fish were fed twice daily at 3% body weight (b.w.) for the first 3 months and 5% b.w. for the last 2 months. Prawns in T₁ fed diet 1 had significantly higher (P<0.05) weight gain compared with that of T₃. The reference group and T₂ had intermediate values not significantly different from either. Weight gains of catla and rohu were significantly higher in T₁. The feed conversion ratio values of different diets ranged between 1.89 and 2.13. Survival (%) ranged from 90.0% to 95.0% for catla, 87.5% to 92.5% for rohu and 70.0% to 76.3% for M. rosenbergii, and there were no significant differences (P>0.05) among different treatments. Total production ranged between 2196 and 2679 kg ha^?1, with T₁ showing significantly higher production and net profit (taka 56 531.9 ha^?1). The results of the study demonstrated that it is possible to culture M. rosenbergii with carp in polyculture during the winter utilizing the late‐produced PLs. Further study is needed to determine the optimum stocking density of M. rosenbergii in carp polyculture.