Dietary manipulations of arachidonic acid, ARA and eicosapentaenoic acid, EPA may have an influence on pigmentation in common sole larvae (Solea solea L., Linnaeus 1758) which may be related to a "pigmentation window". This is a specific period in the larval ontogeny where nutritional factors determine pigmentation. Malpigmentation defined as hypomelanosis was significantly related to elevated dietary and larval ARA contents, but not to EPA. The study reports evidence for a pigmentation window, as larval sensitivity to ARA or its derivatives was much higher during pre metamorphosis, than during metamorphosis.
Initiation of metamorphosis (i.e. start of eye migration) was related to the size of larvae and not related to ARA or EPA content. Dietary EPA or DHA did not retard the advance of eye migration. More than 90 % of highly malpigmented juveniles, (i.e. "albinos") had a permanent aberrant eye migration, which was not related to dietary treatments. This malformation was not observed in normal or slightly malpigmented juveniles. Mean larval ARA tissue contents, malpigmentation and prostaglandin, PGE2 tissue contents were significantly positively correlated. PGE2 levels and pigmentation were not affected by dietary or larval EPA contents. Consequently ARA induced prostaglandins are suggested to be involved in malpigmentation in common sole.