Mmbaga, Rehema Salim2021-11-092021-11-092020Mmbaga R.S (2020) Evaluation of aquatic macroalgae as source of omega-3 (n-3 LC- PUFA) in the Nile tilapia (Oreochromis niloticus). Master dissertation, University of Dar es Salaam. Dar es Salaamhttp://41.86.178.5:8080/xmlui/handle/123456789/16377Available in print form, East Africana Collection ,Dr.Wilbert Chagula Library,Class mark (THS EAF SH167N54T34M633)In aquaculture, nutrition is an important variable as it determines much of the production cost. Fish feed formulation is a very critical procedure in aquaculture in order to enhance optimal fish growth performance, health and eventually income generation. In this present study, aquatic macroalgae (Lemna minor and Eucheuma spp) were evaluated for their source of omega-3 (n-3 LC-PUFA) in feeding Nile tilapia (Oreochromis niloticus). This was achieved by determination of proximate composition (moisture, crude protein, crude lipid, crude fibre, ash and nitrogen-free extracts) of the Lemna minor and Eucheuma spp. Furthermore, growth performance and feed utilization were measured based on daily weight gain, specific growth rate and feed conversion ratio at 0% 5% 10% 15% and 20% inclusion levels. Finally, the effects of the feed ingredients on the Whole-body composition specifically on the Omega-3 and 6 were assessed. This was achieved in four main steps; sample preparation, lipid extraction, methylation and fatty acid analysis. Results of the proximate composition showed that ash, ether extract. Crude protein, dry matter and crude fibre were the main constituents in feed ingredients. On the other hand, Nile tilapia fed with Lemna minor based diet at 15% inclusion level perfomed better in growth and feed utilization (ANOVA, p<0.001). in terms of fatty acid composition, Lemna minor based diet fed at 5% inclusion showed higher composition of Omega-3 fatty acid unlike the Eucheuma spp which showed no significant difference (ANOVA, p = 0.076). These results implied that feeding Nile Tilapia with Lemna minor that is readily available could be used to replace the expensive fish meal thus reduce the cost of fish farming. Moreover, the use of this macroalgae can improve the growth performance and health status of the fish; thus improving the livelihood of small-scale fish farmers through production of quality fishenNile tilapiaOreochremis niloticusCultured Nile TilapiaOmega-3 PUFATanzaniaThesis