Oplegnathidae is a family of marine fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 within the Perciformes

Perciformes

The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...

 commonly known as knifejaws; some species are known as beakfish. It contains a single genus, Oplegnathus. The largest, the Cape knifejaw, can reach a maximum length of about 90 cm (35 in). Knifejaws have teeth fused into a parrotlike beak in adulthood. They feed on barnacles and mollusks, and are fished commercially

Commercial fishing

Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...

. They are found in the north-western Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 (e.g. Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

), in the southern half of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, in the Galapagos, Peru

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

, and Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, and in Southern Africa

Southern Africa

Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...

.

Species

• Cape knifejaw, Oplegnathus conwayi Richardson, 1840
• Striped beakfish
  Striped beakfish
  The striped beakfish, Oplegnathus fasciatus, also called the barred knifejaw or the striped beakperch, is a tropical fish found primarily in Japanese waters, and its main habitat are coral reefs. It has been sighted twice in Malta and only once in Hawaii.While old, the fish is distinguished by...
  
  , Oplegnathus fasciatus (Temminck & Schlegel, 1844)
• Pacific beakfish, Oplegnathus insignis (Kner, 1867)
• Mozambique knifejaw, Oplegnathus peaolopesi Smith, 1947
• Spotted knifejaw, Oplegnathus punctatus (Temminck & Schlegel, 1844)
• Natal knifejaw, Oplegnathus robinsoni Regan, 1916
• Knifejaw, Oplegnathus woodwardi Waite, 1900