Enhancing performance and fatty acids composition of nile tilapia (Oreochromis niloticus) through housefly maggots (musca domestica) meal cultured on aquatic macrophytes

M. Sc. DissertationFish forms an integral part of human diet in Tanzania being rich in protein and Omega 3 fatty acids (ω-3FAs) which are important for growth and proper functioning of human body. The amount of ω-3FAs and performance of tilapia (O. niloticus), the most cultured and consumed fish in Tanzania reported to be low due to inadequate of quality feeds. This study was conducted to compare the effect of three substrates on yield and composition of housefly maggots (HFM); assessed growth performance of O. niloticus fed HFM were mixed with other ingridients and investigated the enhancement of omega 3 fatty acids composition in the produced O. niloticus. The used substrates for HFM production were poultry manure (HFMChick), Lemna species of freshwater macrophytes (HFMLemn) and Eucheuma species of marine macrophytes (HFMEuch). The produced housefly maggots were then used to formulate nine isonitrogenous diets with 35% crude protein and two diets; one contained 5% of fish meal and the other diet containing soybean meal as protein sources. Diets were named as SBM, FM, HFMChick, HFMLemn and HFMEuch, denoting soybean meal, fish meal, and housefly maggots cultured on poultry manure, housefly maggots cultured on Lemna species of freshwater macrophyte and housefly maggots cultured on Eucheuma species of marine macrophyte, respectively. Eight weeks feeding trial was carried out on triplicate groups of ten fish (1.9–2.2 g) in recirculation aquaculture systems (RAS). Fingerlings were randomly allocated to the treatments. The fish were fed up to 5% of their body weights twice daily from 09:30 to 09:45hours in the morning and 16:30 to 16:45 hours evening throughout the experimental period. Effect of inclusion levels of HFM and other diets on fish growth, feed utilization and ω-3FAs were determined. Gas chromatography mass spectrometer (GC-MS) was used to analyze the composition of Omega 3 fatty acids. Results showed that the yields of HFM from poultry manure and Eucheuma species of marine macrophytes (HFMEuch) substrates were significantly higher (P<0.05) than those from Lemna species of freshwater macrophyte. The protein content of HFM from Eucheuma species of macrophyte was significantly higher (P<0.05) than those from poultry manure and Lemna species of freshwater macrophyte. Fish fed on diets containing HFMEuch and FM had significantly higher (P