Partial replacement of fish meal by T-Iso in gilthead sea bream (Sparus aurata) juveniles diets

The aim of this study was the evaluation of microalga Isochrysis sp. T-Iso in partial substitution of fish meal and the study of the effects on gilthead sea bream (Sparus aurata) perform- ances and chemical composition of fillets. The results show that the microalga T-Iso nutrients support growth better than control diets, and the chemical composition of sea bream fillets also meets the needs of consumers for healthy diets. T-Iso resulted highly digestible, and support the best perform- ances of fish fed on 70% alga diet probably due to its high protein efficiency in comparison to other diets. The presence of a high quantity of cyclic isoprenoid could explain this high efficiency of T-Iso. Gilthead sea bream fed on 70% T-Iso showed fillets with a low level of protein and a high level of fat; moreover, their somatic indexes were higher than those of fish fed other diets. Highest percentage T- Iso diet showed the highest amount of the sum of saturated fatty acids, mainly due to myristate and palmitate. On the contrary, the sum of polyunsaturated decreases, mainly because of the reduction of EPA and DHA amounts. If the mass production economical problems are solved, T-Iso will represent a good solution in partial substitution of fish meal.