Physico-Chemical Quality and Plankton Density of Water in Duck-Fish Production Systems

This study was conducted to evaluate the effect of duck manure and spilled duck feed on water quality and production of Oreochromis niloticus in an integrated system with local duck breeds. Fish with an average body weight of 20.17±1.28g, were stocked into experimental ponds (area 72m2 each) at a stocking density of 5 fish/m2 in duplicate. Treatment 1 (T1) was integrated with 12 Mallard ducks (Anas platyrhynchos) while Treatment 2 (T2) was integrated with 12 Muscovy ducks (Cairina moschata). Treatment 3 (T3) was used as control, without integration. Fish in T3 was fed compounded feed of 30% crude protein content three times a day while those in T1 and T2 fed on duck manure and spilled duck feed (15% crude protein content). Water quality parameters of the fish ponds, growth parameters of fish and ducks were monitored. After a 12-week period, mean weight gain of fish were 140.68, 122.11 and 157.19g in T1, T2 and T3 respectively while percentage survival was highest in T3 and lowest in T2. The levels of physico-chemical parameters were generally favourable for fish production and dissolved oxygen (DO) was higher in the integrated treatments probably due to duck activity in the ponds. Plankton analyses shows that duck manure engenders the growth of plankton and this favours the growth of plankton-feeding fish species like O. niloticus. Mallard ducks are recommended for the duck-fish system since they performed better than Muscovy ducks both in survivability and in ability to stimulate physico-chemical and biological processes that engender fish growth.