The Collaborative International Dictionary of English v.0.48:

Hairtail \Hair"tail`\ (-t[=a]l`), n. (Zool.)
   Any species of marine fishes of the genus Trichiurus; esp.,
   Trichiurus lepturus of Europe and America. They are long
   and like a band, with a slender, pointed tail. Called also
   bladefish.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

cutlass fish \cutlass fish\, cutlassfish \cutlassfish\n.
   1. (Zool.) a peculiar, long, thin, marine fish (Trichiurus
      lepturus) of the southern United States and West Indies,
      having a long whiplike scaleless body and sharp daggerlike
      teeth; -- called also frostfish, saber fish, silver
      eel, and, improperly, swordfish; also, several related
      members of the genus Trichiurus. It is closely related
      to snake mackerel.

   Syn: frost fish, frostfish, hairtail.
        [1913 Webster + WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Bladefish \Blade"fish`\, n. (Zool.)
   A long, thin, marine fish of Europe (Trichiurus lepturus);
   the ribbon fish.
   [1913 Webster]