Marine raw material choice, quality and weaning performance of Ballan wrasse (Labrus bergylta) larvae

Abstract

Previous results show that weaning success of Ballan wrasse larvae greatly depends on the quality of the dietary marine raw materials. In the present study, six moist or agglomerated experimental weaning diets containing different combinations of high-quality marine raw materials, being fish meal (FM), cod muscle meal (CMM), shrimp meal (SM) and krill hydrolysate (KH), were tested in a 2-month weaning trial with Ballan wrasse larvae of 34.5 mg initial body weight. Larvae performance was good in all dietary treatments except those fed diet D1 containing only FM. The Ballan wrasse larvae fed weaning diets D4 and D5 containing FM and either SM or KH, respectively, had the highest final body weight (0.7 g) but also the highest mortality (50%). Best weaning survival (77%) was obtained using the dry agglomerated diet D3 containing CMM and SM. During the first month, fish survival correlated positively with dietary free amino acid and soluble protein levels and negatively with the combined levels of dietary lipid oxidation metabolites and ethoxyquin. During the second month, mortality rates were lower in all treatments. Fish larvae final body weight correlated negatively with total dietary fatty acids and positively with dietary cholesterol, phosphorous and DHA/EPA ratio.