A new strategy in rearing of European flounder: using live Enchytraeus albidus to enhance juvenile growth

Abstract

This study reports the use of the annelid worm Enchytraeus albidus as a live feed for reared juvenile European flounder, Platichthys flesus. We investigated growth, lipid composition and mortality in small scale (hundreds of fish) and large scale (thousands of fish) rearing. Live Enchytraeus had a relatively low content of the essential omega-3 fatty acid, docosahexaenoic acid (DHA), but similar levels of other essential fatty acids and amino acids as the normally used commercial dry feed. Despite low DHA levels in live worms, juvenile flounder fed Enchytraeus grew twice as fast as fish fed commercial dry feed. DHA levels in membrane phospholipids of juvenile flounder became depleted when fed Enchytraeus, but this had no apparent negative consequences for development or health of the fish. Our study suggests that the use of Enchytraeus as a live feed for European flounder is feasible at a large scale.