石鲷科为辐鳍鱼纲鲈形目的其中一个科。

本科鱼类体呈长椭圆形到卵圆形，稍侧扁，体辐高。被小型栉鳞，侧线单一且完全，依背缘弯曲。口小不能伸缩，齿愈合形成类似鹦哥鱼之鸟喙状齿板，且非常强壮有利，能轻易咬碎牡蛎坚硬的外壳。但幼鱼时齿为分离的门齿状齿。前鳃盖骨边缘有锯齿。背鳍1枚，基底长，具11至12棘，且硬棘部较软条部之鳍为低。臀鳍基底短，具3棘，和背鳍软条相当。腹鳍在胸鳍基底略后，有腋鳞。尾鳍截平或凹入。小鱼之体色和成鱼差距甚大。体长可达90公分。

Oplegnathus is currently the sole recognized genus in the knifejaw family (Oplegnathidae) of marine perciform fishes. The largest, the Cape knifejaw, can reach a maximum length of about 90 cm (35 in). Knifejaws have teeth fused into a parrot-like beak in adulthood. They feed on barnacles and mollusks, and are fished commercially. They are native to the Indian and Pacific Oceans.