The Collaborative International Dictionary of English v.0.48:

Sea catfish \Sea" cat`fish\ Sea cat \Sea" cat`\ (Zool.)
   (a) The wolf fish.
   (b) Any marine siluroid fish, as Aelurichthys marinus, and
       Arinus felis, of the eastern coast of the United
       States. Many species are found on the coasts of Central
       and South America.
       [1913 Webster]

WordNet (r) 3.0 (2006):

sea catfish
    n 1: any of numerous marine fishes most of which are
         mouthbreeders; not used for food