| Summary: | Salmonids, gilthead sea bream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax L.) play a lead role in the European fish production; however, other farmed fish species are required to differentiate and widen the market supply. Flatfish have long been of interest for aquaculture in Europe. In particular, turbot (Psetta maxima) is the most important cultured flatfish species in Europe, widely reared also in other countries such as East Asia, whereas the sole species common sole (Solea solea) and Segenegal sole (Solea senegalensis) represent an interesting alternative for the diversification of the European and Italian aquaculture, due to the high price and high market demand. To date, the production of these species in Europe and Italy are still minimal compared to other species and further improvement are needed to achieve a full sustainability of the production cycle. Above all, pursuing the ideal feed formulation and an adequate nutrient utilization are of particular relevance for the success of the aquaculture production of any given species. In this context, a critical review of our studies aimed at optimizing the diets for these flatfish species and conducted during the last ten years will be presented. Results indicated that soles species require innovative ingredients and have specific nutritional needs to improve feed intake and growth. In particular different dietary protein levels demonstrated a considerable influence on growth, feed utilization and nitrogen excretion with the highest growth and feed utilization achieved with a diet containing 57 % of crude protein (1). A feeding trial with different dietary energy levels evidenced that increasing dietary lipid level lead to a substantial decline in performance and affect gut health. Dietary lipid levels higher than 12 % depress growth and lipid utilization. High lipid diets lead to moderate to severe intestinal steatosis and ultrastructural evaluations display cellular suffering due to a lipid overload. Soybean meal (SBM) seems to be a ...
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