Six months (Jun 7 to November 22/ 2010) feeding trial was conducted to investigate the effects ofrnfeed quality on growth performance and water quality in cage culture system of mixed-sex Nilerntilapia (Oreochromis niloticus) in Lake Hora-Arsedi using fifteen suspended 1 m3 net cages. Therninitial length and weight of the fish ranged from 119.32 Â± 1.44 to 125.00 Â± 1.50 mm and 42.80 Â±rn2.53 to 43.51 Â± 2.36 gm, (mean Â± SD), respectively. Fish diets were prepared from three kinds ofrnlocally available plant protein source feeds, i.e. oil seed cake (O), mill sweeping (M), and ricernbran (R). In all the combination 20% of blood and bone meal (B) was added to increase therncrude protein level and supplement growth limiting mineral, phosphorus. Therefore, fourrncombination of feeds were prepared as diet-1 (ROM+B), 22.87% crude protein (CP); diet-2 (RMrn+ B), 22.22% CP; diet-3 (MO+B), 22.00% CP, and diet-4 (RO+B), 24.28% CP). About 26.67%rneach of plant protein source ingredient was in diet-1, whereas 40% of it in the otherrncombinations. There was a triplicate of control cages in which fishes were provided with only thernnatural feeds. Each treatment was assigned to triplicates of 100 fish in a completely randomizedrndesign along the U-shaped jetty (walkway). The fish were fed sinking extruded feeds, 3% of theirrnbody weight, twice a day manually using feeding tray. The results showed significant differencesrnamong the test diets. Diet-1 gave the best mean weight gain (MWGs) of 197.38 Â± 5.57 followedrnby diet-3 with MWGs of 182.16 Â± 4.12, diet-2 with MWGs of 169.27 Â± 6.31. Diet-4 and therncontrol gave MWGs of 146.27 Â± 6.82 and 80.62 Â± 3.34 gm, respectively. MWGs in treatment fedrnwith diet-1 were significantly higher (P < 0.05) than MWGs of other treatments. Mean DGRrnranged from 0.28 for the control treatment to 0.92 for the fish fed with diet-1. Specific growthrnrate was also highest in the treatment fed diet-1 (0.9%/ fish) and lowest in the control (0.38%/rnfish). Food conversion ratio and efficiency were best with diet-1, followed by diet-3 and leastrnwith diet-4. Visceral to body weight ratio for the treatment fed with diet-1 was significantlyrnbetter (P < 0.05) than the values for other treatments. Percentage survival ranged from 80% inrnthe control to 94% in cages fed with diet-1. The study showed that diet-1 can be effectively usedrnin the diet of O. niloticus and also in terms of cost it sees more efficient than other followed byrndiet-3. This study also showed that the feeds did not bring any effect on water quality at least inrnexperimental level.rnKey words: Economic analysis; feed conversion;mill sweeping, rice bran; oil seed cake