The present study deals with the effect of four commercially prepared diets on the length-weight relationship, condition factors, growth performance and feed utilization of the cichlid fish, Oreochromis niloticus fingerling reared in glass aquaria. The major components of diets included proteins, fats and carbohydrates of each feed type. The diets were analyzed for verification of values written on its commercial label. Data showed that, the standard length of the fish fed on the different diets did not vary significantly where it ranges between 6.28 ± 0.9 cm in diet II to 6.66 ± 0.8
cm in diet I. The same pattern of change was also noticed in comparing the weight of fishes fed on the four diets. Data indicated that, fish feeding on diet IV demonstrate the lowest weight being on the average of 8.86 ± 1.97 gm, while, fish feeding on diet I showed the highest weight being averaged 10.37 ± 3.2 gm. The growth of fish is nearly isometric in the first three diets and negative allometric in the fourth one. The values of condition factors are slightly differences among different diets. The highest value (3.46) of coefficient of condition (k) was recorded in the fish fed on diet II and
the lowest value (3.09) in the fish fed on diet III. The highest average value (1.07) of the relative condition factor (kn) and the lowest (0.90) were recorded in the fish fed on diet III. The lowest value of total weight gain, average daily gain and specific growth rate were detected in the fish fed on diet IV. The value of feed intake of diet I
is better than the values obtained from the other feed diets. The best feed conversion ratio (1.87) was recorded in the fish fed on diet II. The lower protein efficiency ratio (0.25) was recorded with diet IV and the higher protein efficiency ratio (0.53) was recorded with diet II.