[Pigmented formations in the redfish Sebastes mentella]

The study was carried out on 34,960 specimens of redfish out of which 103 individuals were examined histologically. The black spots proved to be superficial (48) and deep melanosis (24). Skin pterinophorosis was revealed in 20 cases. 24 fishes showed benign chromatoblastomas, among them: 14 melanomas, 5 pterinophoromas and 5 pterinomelanophoromas. The tumours occurred only against a background of the spots above 20 cm2 which were observed in 2.4% of fish of the given population. The major part (76.2%) of pigmented lesions did not exceed 5 cm2. 97.6% of spots in females were found between the pectoral and the first dorsal fins, 84% of spots in males--on the head and caudal fin. The pigmented spots in females occurred 2-5 times more often. Genetic factors are, probably, responsible for pigmented neoplasms and lesions in redfish.