Longnose Lancetfish
Scientific Name Alepisaurus ferox
Conservation Status Data Defficient
Family Chordata
Habitat Temperate Ocean floors
Food Small Crustaceans and mollusks

Lancetfishes are large oceanic predatory fishes in the genus Alepisaurus ("Scaleless lizard"), the only living genus in the family Alepisauridae.

Lancetfishes grow up to 2 metres (6.6 ft) in length. Very little is known about their biology, even though they are widely distributed in all oceans, except the polar seas. Specimens have been recorded as far north as Greenland. They are often caught as by-catch for vessels long-lining for tuna.

Lancetfish have large mouths and sharp teeth, indicating a predatory mode of life. Their watery muscle is not suited to fast swimming and long pursuit, so it is likely that they are ambush predators, using their narrow body profile and silvery colouration to conceal their presence, then use their large dorsal fin to generate large acceleration, and large mouth and teeth to engulf prey before it can escape. That said, stomach content studies have revealed that they feed mainly upon planktonic crustaceans, squid and salps, as well as other fish. They have also been shown to be cannibalistic. They are preyed upon by opah, sharks, albacore, yellowfin tuna, and fur seals.

There are no commercial fisheries for lancetfishes. Their flesh is watery and gelatinous and, although edible, would prove difficult to utilize. They are caught as bycatch by tuna fisheries, and are seen as a pest, taking bait intended for more valuable species. Anecdotal evidence suggesting that they have an aphrodisiac effect is likely to be an urban myth.