Evaluation of microalgae‐supplemented diets and enriched decapsulated artemia cyst powder as novel diets for post‐weaned common sole (Solea solea) larvae

ABSTRACT The current study evaluated the use of two supplemental microalgae, Spirulina platensis and Tetraselmis chuii, and decapsulated artemia cysts as novel diets for post‐weaned common sole (Solea solea) larvae. Four isonitrogenous (55% CP), isoenergetic (22 MJ kg−1) post‐weaning diets were prepared; a control, algae‐free diet and two control diets supplemented with 50 g kg−1 diet of dried S. platensis (SD) or T. chuii (TD). The fourth diet consisted only of decapsulated artemia cyst powder (AD), enriched with 50 g kg−1 diet of docosahexaenoic acid (DHA). A fifth, commercial marine larval diet was used as a reference diet, for comparison. The diets were fed to S. solea larvae (10 mg fish−1, 42 days post‐hatch), at a daily rate of 20% of their live weight, five times a day, for 28 days. The results indicated that AD diet induced the highest growth rates, followed by TD‐ and SD‐supplemented diets, respectively, whereas the control and commercial diets displayed the lowest performance. SD‐ and AD‐fed groups had the highest body protein contents, while body lipids were not significantly affected by dietary treatment, except the AD group which exhibited significantly higher lipid level. The results also indicated that AD‐ and algae‐supplemented diets produced significantly higher survival rate and body n‐3 HUFA, EPA, DHA and n‐3/n‐6 ratio than the control and commercial diets. This study demonstrated that enriched decapsulated artemia cyst powder could be an excellent post‐weaning diet for common sole (S. solea) post‐larvae. The present results also suggest that inert microdiets enriched with 50 g kg−1 diet of Spirulina platensis or Tetraselmis chuii can serve as excellent diets for these post‐larvae.