The Collaborative International Dictionary of English v.0.48:

Houndfish \Hound"fish\, n. (Zool.)
   Any small shark of the genus Galeus or Mustelus, of which
   there are several species, as the smooth houndfish (Galeus
   canis), of Europe and America; -- called also houndshark,
   and dogfish.
   [1913 Webster]

   Note: The European nursehound, or small-spotted dogfish, is
         Scyllium canicula; the rough houndfish, or
         large-spotted dogfish, is Scyllium catulus. The name
         has also sometimes been applied to the bluefish
         (Pomatomus saltatrix), and to the silver gar.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dogfish \Dog"fish`\, n. (Zool.)
   1. A small shark, of many species, of the genera Mustelus,
      Scyllium, Spinax, etc.
      [1913 Webster]

   Note: The European spotted dogfishes (Scyllium catudus, and
         Scyllium canicula) are very abundant; the American
         smooth, or blue dogfish is Mustelus canis; the common
         picked, or horned dogfish (Squalus acanthias)
         abundant on both sides of the Atlantic.
         [1913 Webster]

   2. The bowfin (Amia calva). See Bowfin.
      [1913 Webster]

   3. The burbot of Lake Erie.
      [1913 Webster]