Response of European sea bass (Dicentrarchus labrax) to diets including marine microalgae biomass as sustainable ingredients

For a sustainable aquaculture industry, current levels of fish meals/oils in aquafeeds need to be drastically reduced and mostly replaced by alternate counterparts. In this contest, the use of marine microalgae in aquafeeds has recently attracted much scientific attention due to their high protein content and lipid levels, including ω-3 long-chain PUFAs. In the present study, we investigated the growth performance and body composition of sea bass (Dicentrarchus labrax, L., 1758) in response to diets where graded levels of a blend of two marine microalgae (Isochrysis aff. galbana (T-ISO) and Tetraselmis suecica) were included in low fish meal/oil diets. The microalgae-containing aquafeeds were also compared to a diet (negative control) with a 30:70 fish to vegetable protein-lipid ratios. Fish given the positive control feed and those fed diets including graded levels of microalgae showed similar growth performance and feed conversion ratios which were significantly better than those attained by fish fed the negative control diet (B.W. 420 vs 388 g, SGR 0.69 vs 0.61, FCR, 1.7 vs 1.9, p<0.05). The effects of the dietary microalgae inclusion on fillet fatty acid composition and intestinal brush border enzyme activity were also considered.