First record of hyper melanosis in the Patagonian redfish Sebastes oculatus Valenciennes, 1833 (Scorpaenidae) in the southeastern Pacific Ocean

The coloration pattern alteration occurs at a low frequency in fish. The excesses of dark pigments in living organisms are known as melanism or melanosis, but a total blackening of the skin is known as hyper melanism or hyper melanosis. Little is known about why the extreme conditions of albinism and melanosis occur among fish. To date, there are no records of melanism for the genus Sebastes. Here, we report the first case of hyper melanosis in rockfish Sebastes oculatus (Patagonian redfish) in the southeastern Pacific Ocean. In 2005, small-scale fishers from Quintay Beach (Valparaiso, Chile) captured a single individual of Patagonian redfish covered with an excess of dark pigmentation. The specimen had a total length of 35.5 cm, and we followed the literature available to determine its morphometric and meristic features. The measurements led us to conclude that the specimen was a black S. oculatus with a rare melanosis condition. Our finding contributes to the knowledge of this species, and we infer that this melanosis case was caused by genetic heritage or some intergenetic hybridization. Still, genetic studies are necessary to confirm this hypothesis.