scales can be further subdivided into three types:
* Crenate scales, where the margin of the scale bears indentations and projections.
* Spinoid scales, where the scale bears spines that are continuous with the scale itself.
* True ctenoid scales, where the spines on the scale are distinct structures.

Most ray-finned fishes have ctenoid scales. Some species of flatfishes have ctenoid scales on the eyed side and cycloid scales on the blind side, while other species have