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]