The Collaborative International Dictionary of English v.0.48:

Spoutfish \Spout"fish`\ (-f[i^]sh`), n. (Zool.)
   A marine animal that spouts water; -- applied especially to
   certain bivalve mollusks, like the long clams (Mya), which
   spout, or squirt out, water when retiring into their holes.
   [1913 Webster]