In the present study potential of two oil resources, canola oil and flaxseed oil were examined as replacements for dietary fish oil in diets of fingerling rainbow trout ( Oncorhynchus mykiss ), during 8 weeks period. Two hundred and ten individual fish with mean initial body weight of 16.49±0.46 g in 7 triplicate groups (21 replicates, 10 fish per replicate) reared in semi recirculated system with mean water temperature of 13.61±1.27 o C. Seven iso-nitrogenous (protein: 30.66±0.47%) and iso-lipidic (lipid: 16.09±0.29%) experimental diets were formulated from 100% fish oil, 100% canola oil, 100% flaxseed oil, 1:1 blends of fish and canola oils, 1:1 blends of fish and flaxseed oils, 1:1 blends of canola and flaxseed oils and 1:1:1 blends of fish, canola and flaxseed oils. At the end of the experiment, 2 fish from each replicate were sacrificed for body composition and fatty acid profile analyses. Except for protein and lipid percentage, moisture and ash content of the body were not significantly influenced by the type of the diets. The highest content of protein and lipid in flesh were observed in treatment 4, which showed significant differences with treatments 5 and 7, and treatments 2, 5, 6, 7, respectively (p 0.05). However, there were no significant differences in final body weight, specific growth rate, weight gain Percentage, food conversion ratio, survival and hepato-somatic index among the dietary treatments. The highest amount of condition factor were observed in diets with 100% fish oil that being significantly different from treatments 3, 5, 6, 7 (p 0.05). The highest amount of relative carcass weight were observed in diets with 100% canola oil that being significantly different from treatment 7 (p 0.05). Moreover, the highest PPV and PER value were observed in treatment 3, that showed significant differences with treatments 1, 2, 4, 5 and 7 (p 0.05). The results of fatty acid profile revealed that flesh fatty acid composition is affected by dietary fatty acid composition. In addition the highest amounts of HUFAs was detected in fish fed 100% fish oil, that were significantly different from other treatments (p 0.05). However, complete replacement of fish oil with flaxseed oil or 50% fish oil with canola oil can provide enough HUFAs that required for daily human consumption. In all treatments, the PUFA/SFA and n6/n3 ratios, was higher than 0.45 and lower than 4, respectively. In general, results of present study indicate that, rainbow trout can be reared on a diet that fish oil has been replaced with canola and flaxseed oils, without having adverse effects on different aspects of fish performance. Key words: Rainbow trout ( Oncorhynchus mykiss ), Fish oil, Canola oil, Flaxseed oil, Growth, Fatty acid composition