Oplegnathus is currently the sole recognized genus in the knifejaw family (Oplegnathidae) of marine centrarchiform ray-finned fishes. The largest, the Cape knifejaw, can reach a maximum length around 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.[1]
The earliest records of knifejaws are fossilized beaks, with attached teeth, known from middle Eocene-aged sediments of the La Meseta Formation of Antarctica. Their early occurrence in Antarctica supports it having temperate climate during the Eocene, and that knifejaws had a wider distribution in the past than today.[2]
The currently recognized species in this genus are: