Trachidermus fasciatus is a species of fish in the superfamily Cottoidea, the sculpins, and the only member of the monotypic genus Trachidermus. Its common name is roughskin sculpin. It has also been called four-gilled perch. It is native to the coastlines of China, Japan, and Korea, where it occurs at the mouths of rivers. This fish lives in rivers, estuaries, and coastal ocean waters. It is catadromous; adults spawn on mudflats at the river mouths, and after hatching, the juveniles swim upstream to freshwater river habitat.