Growth and Fatty Acid Composition of Juvenile Olive Flounder Paralichthys olivaceus Fed Diets Containing Different Levels and Ratios of Eicosapentaenoic Acid and Docosahexaenoic Acid

Abstract

This study was carried out to investigate the influences of dietary levels, ratios and sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the growth and fatty acid compositions of juvenile olive flounder Paralichthys olivaceus. Sixteen diets containing five levels of EPA (0.5%, 1.0%, 1.5%, 2.0%, and 4.0%), five levels of DHA (0.5%, 1.0%, 1.5%, 2.0% and 4.0%), three ratios of EPA/DHA (75/25, 50/50 and 25/75), two levels of squid liver oil (5% and 10%) and a control diet containing 5% soybean oil were hand-fed to triplicate groups of fish (average weight, 9.7 ± 0.3 g) for 8 weeks. Survival, specific growth rate, feed efficiency and protein efficiency ratio of fish were not affected by dietary EPA and DHA levels or ratios. Also, the dietary treatment had no significant effect on the lipid and protein contents of muscle and whole body of fish. A corresponding increase in the EPA and DHA contents of fish occurred with increasing EPA and DHA levels in their diets. Our results suggest that juvenile olive flounder require a dietary EPA level of approximately 0.32% in the presence of 0.74% DHA for sui table survival and growth, and that EPA and DHA levels in fish muscle can increase to as much as 32% and 53%, respectively, of the total fatty acid content.