Ctenoid Scale

a variety of bony scale in bony fishes; the posterior margin of the scale bears a comb of small teeth or spines. Ctenoid scales are typical chiefly for higher bony fishes, such as the Perciformes, but they also occur in fishes of a lower organizational level (for example, in some Clupeiformes and Gadiformes). It is supposed that the spikes on ctenoid scales improve the hydrodynamic properties of the fish’s body.