bluefish \blue"fish`\, n. zool.
   1. a large voracious fish pomatomus saitatrix, of the
      family carangidae, valued as a food fish, and widely
      distributed on the american coast. on the new jersey and
      rhode island coast it is called the horse mackerel, in
      virginia saltwater tailor, or skipjack.
      1913 webster

   2. a west indian fish platyglossus radiatus, of the
      family labridae.
      1913 webster

   note: the name is applied locally to other species of fishes;
         as the cunner, sea bass, squeteague, etc.
         1913 webster
see also:
pomatomus saitatrix carangidae horse mackerel saltwater tailor skipjack platyglossus radiatus 
labridae