Аннотация:Until recently, only one freshwater form of trout of the species Salmo mykiss know to exist in Kamchatka water bodies. Recently, trout with features common to the American species - the cutthroat trout S. clarki Richardson - have been, caught in the Tigil river basin in equal numbers with the typical mikizha. Specimens with the pronouced traits of the mikizha and coastal cutthroat trout occur here as single specimens. The trout resembling the red band trout of the species S. mykiss of North America and combining the features of both species to a certain extent is the most abundant. In general the trout of the Tigil basin constitute a series at transitional forms, the extreme variants of which are distinguished more sharply from each other by the number and arrangement of the black marks on the head and body, by the brightness and size of the orange spot on the throat (the cutthroat mark),by the rain bow band along the lateral line, and by the number and extent of development of the basibranchial teeth. The coastal cutthroat trout and redband trout, until recently known only in America, are the most primitive representatives of the group. It is possible that the Kamchatka primitive forms diverged from each other to a lesser extent that the American representatives and that northeast Asia was the place where the divergence began.