The Collaborative International Dictionary of English v.0.48:

Pomacentroid \Po`ma*cen"troid\, a. [Gr. ? a cover + ? a prickle
   + -oid.] (Zool.)
   Pertaining to the Pomacentrid[ae], a family of
   bright-colored tropical fishes having spiny opercula; --
   often called coral fishes.
   [1913 Webster]