Influence of lipid composition of live feed on growth,survival and pigmentation of turbot larvae

The effect of different lipid compositions of live feed on the survival, growth rate and pigmentation success of turbot larvae, Scophthalmus maximus (L.), was investigated. Rotifers, Brachionus plicatilis, together with the algae Tetraselmis sp., were administered until day 12, and Artemia was fed until day 27. The experimentally treated live feeds were enriched with four formulated emulsions, resulting in a gradient in the relative contents of 3 HUFA (highly unsaturated fatty acids) and in DHA (docosahexaenoic acid, 22:6 3)/EPA (eicosapentaenoic acid, 20:5 3) ratios in both the rotifers and Artemia.There were no differences in larval growth rate, and only small differences in survival rate throughout the feeding experiment, probably because of satisfactory levels of 3 HUFA in the live feed to sustain growth and survival. A correlation was obtained between the percentage of completely pigmented 27 d old turbot and the DHA/EPA ratio in the total lipids of 12 d old larvae, which again was correlated with the corresponding ratio in the live feed used. The results suggest that normal pigmentation in turbot requires dietary DHA in the early larval feeding period, and that this requirement cannot be replaced by EPA.