The Collaborative International Dictionary of English v.0.48:

Coalfish \Coal"fish`\, n. [Named from the dark color of the
   back.] (Zool.)
   (a) The pollock; -- called also, coalsey, colemie,
       colmey, coal whiting, etc. See Pollock.
   (b) The beshow or candlefish of Alaska.
   (c) The cobia.
       [1913 Webster]