Effects of nutritional enhancement of live food organisms on growth and survival of barramundi, Lates calcarifer (Bloch), larvae

Larval and juvenile barramundi, Lates calcarifer (Bloch), were reared intensively on test diets comprising nutritionally supplemented and unsupplemented rotifers, Brachionus plicatilis Muller, and brine shrimp, Artemia salina L. Both growth and survival of barramundi larvae fed on nutritionally supplemented brine shrimp were superior to those of larvae fed on untreated brine shrimp. Barramundi larvae fed diets incorporating untreated brine shrimp exhibited a mortality syndrome which commenced from 20 to 30 days after hatching and resulted in almost total mortality within the next 10 days. Analyses of the proximate, fatty acid and amino acid composition of the live food organisms used in the test diets, and reference samples comprising barramundi egg yolk and extensively reared juvenile barramundi, suggest that this mortality syndrome was primarily associated with the fatty acid composition of the food organisms, particularly the relative amount of 20:5n-3 in the brine shrimp fed to the larvae. These results, and the work of other authors, indicate that there are two mortality syndromes which affect intensively cultured L. calcarifer larvae