Effects of all-male, mixed-sex and all-female freshwater prawn in polyculture with major carps and molas in the fallow rice fields

摘要

This study was conducted to evaluate the effects of all-male, mixed-sex and all-female freshwater prawn (Macrobrachium rosenbergii) in a polyculture with major carps (Catla catla and Labeo rohita) and self-recruiting small fish molas (Amblypharyngodon mola) in the fallow rice fields of Bangladesh. There were three treatments with three replicates. All ponds were stocked with carps and molas plus either all-male prawns (treatment MP), mixed-sex prawns (MFP) or all-female prawns (FP). Prawn, mola, catla and rohu were stocked 20 000, 20 000, 1750 and 750 hap#, respectively, in all treatments. The prawns were fed twice daily, starting at 8% body weight and gradually reduced to 3% body weight. The fish were fed in the morning with mustard oil cake and rice bran (1:2 ratios) at 3% body weight. Significantly higher production of prawns (697 kg hap#) was obtained in treatment MP, which yielded 34.7% and 56.2% more production than MFP and FP respectively. Significantly higher total production of 1620 kg hap# and a higher benefit-cost ratio of 2.10:1 were also obtained in treatment MP. It can be concluded that an all-male prawn culture is economically more viable than all-female and mixed-sex prawn cultures, along with other fish like major carps and the nutrient-dense molas in the polyculture.