Source : Webster's Revised Unabridged Dictionary (1913)

Roundfish \Round"fish\, n. (Zo["o]l.)
      (a) Any ordinary market fish, exclusive of flounders,
          sole, halibut, and other flatfishes.
      (b) A lake whitefish ({Coregonus quadrilateralis}), less
          compressed than the common species. It is very
          abundant in British America and Alaska.