ganoid

Of, relating to, or characteristic of certain bony fishes, such as the sturgeon and the gar, that have armorlike scales consisting of bony plates covered with layers of dentine and enamel.

A ganoid fish.

[From New Latin Ganoideī, subclass name, from Greek ganos, brightness, gladness, from ganusthai, to rejoice.]

The noun has one meaning:

Meaning #1: primitive fishes having thick bony scales with a shiny covering
  Synonym: ganoid fish