Experiments were conducted to determine the differences of two different commercial feeds (which contain protein levels of % 46.65 and % 44.88) on the growth of the Rainbow trout (Oncorhynchus mykiss W. 1792) grown in sea water. Living initial average weights first group 102.15±2.037 g and second group 104.15±1.98 g while found that end of experiment final average weights first group 279.31±5.46 g and second group 284.18±6.40 g. Living body weight gained in first group 177.16 g and in second group 179.3 g were obtained. Feed conversion rate were found that of groups respectively 1.25 and 1.19. The higher average weight gained, were produced by diet B, namely the diet that contained % 46.65 of animal proteins and weren't significant. All the fish were fed two times daily with the different commercial diet during experimental period. Experimental period were planned trouts when to arrive portion size. This period consist of total 64 days from December 29 to March 2, 1994.