The effect of essential fatty acids (EFA) and vitamin C-enriched Artemia nauplii on growth, survival, and resistance to temperature (high) stress in rainbow trout larvae reared in tanks were investigated. The larvae (average weight 120.43mg±13.5) were fed 6 times daily starting at the onset of exogenous feeding for 1 week. Triplicate groups of fish were offered one of four treatments (1) commercial starter food for rainbow trout, (2) newly hatched Artemia nauplii (unenriched), (3) highly unsaturated fatty acid (HUFA) + vitamin C-enriched Artemia nauplii and (4) combination of 10% HUFA + vitamin C enriched nauplii and commercial starter food. After 1 week, all groups of fish were switched to the commercial diet for an additional period of 3 weeks. Statistical analysis of growth after the first week and at the end of the experiment, showed that growth of larvae in various treatments was significantly different (P<0.05). After 4 weeks, the larvae in treatment 3 with the average weight of 657.50 ± 57.93 mg had the highest body weight (P<0.05). The highest percentage of survival (96%) was observed in treatment 3 (P<0.05). Proximate compositions of trout larvae after one week feeding with experimental diets showed that the protein in the larvae of treatments 3 and 4 was significantly different compared to other treatments (P<0.05). The best result of resistance to temperature (up to 24ºC) was observed in larvae reared on treatment 3 with 91.34 ± 1.52 percent (P<0.05)
