The Collaborative International Dictionary of English v.0.48:

Snailfish \Snail"fish`\, n. (Zool.)
   See Sea snail
   (a) .
       [1913 Webster]

WordNet (r) 3.0 (2006):

snailfish
    n 1: small tadpole-shaped cold-water fishes with pelvic fins
         forming a sucker; related to lumpfish [syn: snailfish,
         seasnail, sea snail, Liparis liparis]