The effects of three different combinations of silver carp Hypophthalmichthys molitrix and catla Catla catla density on the production system in all-male freshwater prawn–finfish polyculture ponds were evaluated in triplicate. The stocking density of silver carp and catla, respectively, were maintained at 2000 and 500 ha−1 in treatment SC2000C500, 1500 and 1000 ha−1 in treatment SC1500C1000 and 1000 and 1500 ha−1 in treatment SC1000C1500. Male freshwater prawn Macrobrachium rosenbergii and small fish mola Amblypharyngodon mola densities were fixed in all treatments at 12 000 and 20 000 ha−1 respectively. Management practices were same for all treatments. Blue-clawed male prawns were harvested twice during the 122-day culture at 15-day intervals before the final harvest. Plankton and macro-benthos abundance and water quality parameters (except transparency and chlorophyll a) did not vary significantly (P>0.05) among treatments. Mean final weights of both silver carp and catla were decreased with the increasing of their own stocking density. The treatment SC1500C1000 resulted in 25–32% increased net production of silver carp plus catla (461 kg ha−1) and 20–21% increased net production of all species combined (874 kg ha−1) as compared with the other treatments, although the differences in production of prawn and mola among treatments were not significant.