This study was conducted in nylon net enclosures system with two replicates for each combination to assess the effect of replacing fish meal protein (FMP) with 0, 15, 30, 45 and 60 % of fish waste silage protein (FWSP) or shrimp head silage protein (SHSP) in diets for Nile tilapia (Oreochromis niloticus). The experimental diets were isonitrogenous (crude protein 32 %) and isocaloric (423.70 kcal gross energy/100 g of dry matter). Diets were fed to fingerlings of Nile tilapia (mean weight 12.4 g

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... ±0.3) at 3 % of body weight per day (6 days a week) for 14 weeks. The results indicated that the replacement levels of FMP by FWSP had nonsignificant effects (P >0.05) on growth performance and feed conversion ratio when compared with the control group. On the other hand, as FWSP or SHSP levels increased, PPV (%) decreased with nonnsignificant difference between that receiving 15 % FWSP and the control group. The higher percentage of energy utilization (EU) was achieved by fish fed on the control diet and that fed on diet containing 30 % SHSP with significant (P <0.05) differences from the other groups. Carcass compositions differed marginally in the fish fed the different diets. The results of the economic evaluation manifested that the feed cost and the changes in the cost/kg fish gain were decreased with increasing replacement of FMP by FWSP or SHSP. It could be suggested that fish waste and shrimp head silage are promising alternative protein sources for Nile tilapia to replace FMP with 60 and 30 %, respectively without adverse effects on fish growth.