Effect of different levels of eicosapentaenoic acid and docosahexaenoic acid in Artemia nauplii on growth, survival and salinity tolerance of larvae of the Japanese flounder, Paralichthys olivaceus

Abstract

Variations in growth, survival and salinity tolerance of Japanese flounder larvae were studied after feeding Artemia nauplii enriched with different levels of unsaturated fatty acids. Fifteen-day-old larvae were fed nauplii enriched with various levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 25 days. Growth of larvae was significantly improved by feeding Artemia containing increased levels of n-3 HUFA, but there was no clear difference between the effect of EPA and DHA on growth. In contrast, those fed Artemia enriched in oleic acid showed poor growth and had low survival. Survival of larvae after high salinity water (65‰) treatment (salinity tolerance test) was significantly improved by an increase of DHA content in Artemia, but not by EPA. These results indicate that DHA is superior to EPA as an essential fatty acid (EFA) from view point of the salinity tolerance of the larvae. The DHA requirement of Japanese flounder larvae is suggested to be about 1.6% in the presence of 1.0% EPA dry weight of Artemia nauplii (3.0% total n-3 HUFA).