needlefish, any of the long, slim, primarily marine fishes of the family Belonidae (order Atheriniformes), found throughout temperate and tropical waters. Needlefish are adept jumpers, carnivorous in habit, and distinguished by long, slender jaws equipped with sharp teeth. They are silvery fish, with blue or green backs, and are edible. The family includes some 60 species, the largest growing about 1.2 m (4 feet) long. Among the species are the garfish (Belone belone) of Europe and the houndfish (Tylosurus crocodilus), found everywhere in the tropics.