The Collaborative International Dictionary of English v.0.48:

Ladyfish \La"dy*fish`\, n. (Zool.)
   (a) A large, handsome oceanic fish (Albula vulpes), found
       both in the Atlantic and Pacific oceans; -- called also
       bonefish, grubber, French mullet, and macab['e].
   (b) A labroid fish (Harpe rufa) of Florida and the West
       Indies.
       [1913 Webster]

WordNet (r) 3.0 (2006):

ladyfish
    n 1: game fish resembling the tarpon but smaller [syn:
         ladyfish, tenpounder, Elops saurus]