A Brief Perspective on the Biology of Pigmentation in Freshwater Ornamental Fish

The color pattern of fish is formed/manifested by the distribution and combination of different pigments such as melanophore, xanthophore, erythrophore, iridophore, leucophore, and cyanophore. Coloration is the key factor for ornamental fish and also plays a very significant role in the life history and behavior of fishes, such as in mimicry or predator avoidance, mate selection, etc. The major players of coloration in fish are: melanophore found in melanosome (for black and brown); xanthophore pigment found in xanthosome and carotenoid (for yellow and orange); erythrophore present in erythrosome (for orange and red); iridophore present in platelets (for iridescence); leucophores present in leucosome (for white); and cyanophore present in cyanosome (for blue color). The main sources of carotenoid in fish are dietary or synthetic to achieve the carotenoid pigment in fish body. There is an established molecular signalling pathway through which carotenoids regulate coloration in fish. Besides these, the addition or supplementation of prospective source of carotenoids through diet may also increase the color intensity in fish body. However, interference of several factors may negatively influence the pigmentation in ornamental fish. The present review has covered all these aspects and consulted possible up to date publications to forward a comprehensive understanding on the topic.