CRITICAL INVOLVEMENT OF DIETARY DOCOSAHEXAENOIC ACID IN THE ONTOGENY OF SCHOOLING BEHAVIOR IN THE YELLOWTAIL

To investigate involvement of the central nervous system in the ontoge ny of behaviour, diets of differing quality were used to rear yellowta il Seriola quinqueradiata larvae and juveniles. Artemia nauplii enrich ed with oleic acid (OA), eicosapentaenoic acid (EPA), or two different concentration levels of docosahexaenoic acid (DHA) were fed to yellow tail larvae (L-T 7 mm; 13 days old) for 12 days, and their behavioural development was analysed together with growth, survival, activity and fatty acid composition. Yellowtail fed with DHA-enriched Artemia show ed mutual attraction behaviour at 11 mm L-T, while those fed with OA- or EPA-enriched Artemia did not show this behaviour at the same size. While fish in the OA group showed poor growth, survival and activity i ndex, fish in the EPA group were similar to the two DHA groups. In add ition, most fish tested, including the OA group, showed clear optokine tic responses. Fatty acid composition of the diet was reflected in tha t of the fish body. Therefore, dietary DHA in the larval stage is cons idered to be essential for the development of schooling behaviour in t he yellowtail. (C) 1998 The Fisheries Society of the British Isles.