Source : WordNet®

whitefish
     n 1: any market fish--edible saltwater fish or shellfish--except
          herring
     2: flesh of salmon- or trout-like cold-water fish of cold lakes
        of the northern hemisphere
     3: silvery herring-like freshwater food fish of cold lakes of
        the northern hemisphere
     [also: {whitefishes} (pl)]

whitefishes
     See {whitefish}