The Collaborative International Dictionary of English v.0.48:

Redfish \Red"fish`\ (r[e^]d"f[i^]sh`), n. (Zool.)
   (a) The blueback salmon of the North Pacific; -- called also
       nerka. See Blueback
   (b) .
   (b) The rosefish.
   (c) A large California labroid food fish (Trochocopus
       pulcher); -- called also fathead.
   (d) The red bass, red drum, or drumfish. See the Note under
       Drumfish.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fathead \Fat"head`\, n. (Zool.)
   (a) A cyprinoid fish of the Mississippi valley (Pimephales
       promelas); -- called also black-headed minnow.
   (b) A labroid food fish of California; the redfish.
       [1913 Webster]

WordNet (r) 3.0 (2006):

fathead
    n 1: a man who is a stupid incompetent fool [syn: fathead,
         goof, goofball, bozo, jackass, goose, cuckoo,
         twat, zany]