Effects of introducing ducks into fish ponds on water quality, natural productivity and fish production together with the economic evaluation of the integrated and non-integrated systems

Raising ducks on fish ponds (fish-duck culture) on a commercial scale is a new practice in Egypt, therefore, a study was undertaken to evaluate this p ractice from production, carcass composition and economic viewpoints. Five earthern ponds were used in the non-integrated system (no ducks) where as four earthen ponds, in which each pond was supplied with 125 Pecking duc ks per 0.42 ha, were used for the Integrated system. In both systems, each pond was stocked with four species of fish (common carp Cyprinus carpio, si lver carp Hypophthalmichthys molitrix, Grey mullet Mugil cephalus and tilap ias Oreochromis niloticus and O. aureus) at the same densities. There were no differences in temperature or pH in any of the ponds but diss olved oxygen levels were lower in integrated ponds concomitant with increas ing levels of ammonia, phosphate and nitrate. Water in integrated ponds was richer in natural productivity (phytoplankton and zooplankton) either in s pecies or density when compared with those variables in non-integrated pond s. Fish species reared in integrated ponds exhibited better body weight, food conversion and protein efficiency ratios compared with those of fish specie s in the non-integrated ponds. Fish yield per 0.42 ha produced from the int egrated ponds was significantly higher than that obtained from non-integrat ed ones. Also, body composition of fish species was affected by the type of farming. Carcass crude protein of grey mullet, silver carp and tilapia was improved in the integrated system. The data on return on sales, return on costs, return on equity, pay-back period and break-even point showed that t he integrated system was more profitable than the non-integrated system.