Pelvic fin

Gobiids and lumpsuckers modify their pelvic fins into a sucker disk that allow them to adhere to the substrate or climb structures, such as waterfalls.

[2] In priapiumfish, males have modified their pelvic structures into a spiny copulatory device that grasps the female during mating.

[3] In actinopterygian steady state swimming, the pelvic fins are actively controlled and used to provide powered corrective forces.

[4] In rays and skates, pelvic fins can be used for "punting," where they asynchronously or synchronously push off the substrate to propel the animal forwards.

[citation needed] In zebrafish, the pelvic fin bud starts as a mesenchymal condensation that forms an apical ectodermal thickening.