What is "coregonus ferus"

Gwiniad \Gwin"i*ad\ (gw[i^]n"[i^]*[a^]d), n. [W. gwyniad a whiting, the name of various fishes, fr. gwyn white.] (Zo["o]l.) A fish ( Coregonus ferus) of North Wales and Northern Europe, allied to the lake whitefish; -- called also powan, and schelly. [Written also gwyniad, guiniad, gurniad.]

Powan \Pow"an\, Powen \Pow"en\, n. (Zo["o]l.) A small British lake whitefish ( Coregonus clupeoides, or Coregonus ferus); -- called also gwyniad and lake herring.