Comparison between live food and artificial diet on survival rate, growth and body chemical composition of < i > Oncorhynchus mykiss < /i > larvae

This study was conducted to evaluate the efficacy of live food ( < i > Artemia urmiana < /i > ) and commercial diet in rearing of < i > Oncorhynchus mykiss < /i > larvae. Experiment started when larvae were 0.12g in weight. Triplicate groups of fish were offered one of four treatments: (1) a commercial starter food; (2) live < i > Artemia urmiana < /i > nauplii (for 3 days); (3) live < i > Artemia urmiana < /i > nauplii (for 7 days); and (4) combination of live < i > Artemia < /i > nauplii (5% of food) and the commercial starter food. They were fed four times daily starting at the onset of exogenous feeding, for 1 week. After 1 week, the fish of all groups were shifted to the commercial diet for an additional 3-weeks period to determine the impact of any differences in weight of fish. The result of the present study showed that those larvae fed with combination of < i > Artemia < /i > nauplli and a commercial starter food grew significantly faster than other groups for 4 weeks. Larvae fed with other composition were similar in length and weight (P > 0.05). Survival rates of the trout larvae ranged 86-96% after 1 week and 67-84% after 4 weeks. Larvae survival after 1 and 4 weeks were significantly higher (P < 0.05) in trout larvae fed only on < i > Artemia < /i > nauplii (treatments 2 and 3) than other treatments. The body chemical composition analysis of trout larvae showed only small differences, with the exception of the crude protein and lipid at 4 weeks. The data were analyzed to determine significant differences among treatments by one-way ANOVA. (Statistica v.9, StatSoft Inc.).