Source : Webster's Revised Unabridged Dictionary (1913)

Horsefish \Horse"fish`\, n. (Zo["o]l.)
      (a) The moonfish ({Selene setipinnis}).
      (b) The sauger.

Source : WordNet®

horsefish
     n : any of several silvery marine fishes with very flat bodies
         [syn: {moonfish}, {Atlantic moonfish}, {horsehead}, {horse-head},
          {dollarfish}, {Selene setapinnis}]