It lives in the sea around Hokkaido, the Sea of Japan north of Yamaguchi Prefecture, the Pacific Ocean north of Choshi that East Chiba Prefecture, and offshore of Sakhalin and Alaska. Its body is long, thin and slightly thin. The body surface is slimy. The mouth is very small, eating small amphipods and polychaetes. It's slightly delicious when you dry it and grill it. The name originates from fins that all of those are black. Another species of willowy flounder Tanakius kitaharae (Jordan & Starks, 1904) inhabits the northeastern region without black fins, and this dried adult females are exquisite and very high-grade fish (G. stelleri is inexpensive).