Pigment abnormalities in flatfish

Pigment abnormalities have been reported to occur on both sides of flatfish. Hypomelanosis or pseudo-albinism, characterized by white patches or areas devoid of normal pigmentation on the ocular surface of the skin, is common in both wild and hatchery reared flatfish. The blind side may display hypermelanosis in the form of dark spots, known as ambicoloration of the skin. The etiology of these abnormalities is not well understood. Environmental, nutritional and neurological aspects which may be involved are reviewed and approaches for future research are identified.