Needlefish closely resemble North American freshwater gars (family Lepisosteidae) in being elongate and having long, narrow jaws filled with sharp teeth, and some species of needlefish are referred to as gars or garfish despite being only distantly related to the true gars. In fact the name "garfish" was originally used for the needlefish Belone belone in Europe and only later applied to the North American fishes by European settlers during the 18th century.
Needlefish are slender fish, ranging from 3 centimeters (1.2 in) to 95 centimeters (37 in) in length. They have a single dorsal fin, placed far back on the body, almost opposite to the anal fin. Their most distinctive feature is their long narrow beak, which bears multiple sharp teeth. In most species, the upper jaw only reaches its full length in adulthood, so that the juveniles have a half-beak appearance, with an elongate lower jaw, but a much smaller upper one. During this stage of their life cycle, they eat plankton, switching to fish once the beak fully develops.
Needlefish feed primarily on smaller fishes, which they catch with a sideways sweep of the head. In addition some species will also take plankton, swimming crustaceans, and small cephalopods. Freshwater species are also predatory, with the Asian species at least feeding exclusively on small crustaceans.
Needlefish are most common in the tropics but some inhabit temperate waters as well, particularly during the summer months. Belone belone is a common North Atlantic species that often swims in schools alongside mackerel.
 Danger to humans
Needlefish, like all ray-finned beloniforms, are capable of making short jumps out of the water at up to 38 miles per hour (61 km/h). Since needlefish swim near the surface, they often leap over the decks of shallow boats rather than going around. This jumping activity is greatly excited by artificial light at night; night fisherman and divers in areas across the Pacific Ocean have been "attacked" by schools of suddenly excited needlefish diving across the water towards the light source at high speed. Their sharp beak is capable of inflicting deep puncture wounds, often breaking off inside the victim in the process. For many traditional Pacific Islander communities, who primarily fish on reefs from low boats, needlefish represent an even greater risk of injury than sharks.
Two historical deaths have been attributed to needlefish. The first was in 1977 when a 10-year-old Hawaiian boy, night fishing with his father at Hanamaulu Bay, Kaua'i, was killed when a 3-to-4-foot-long (0.91 to 1.2 m) needlefish jumped from the water and pierced his eye and brain. The second was a 16-year-old Vietnamese boy, stabbed through the heart by the 6-inch (150 mm) spike of a needlefish in 2007 while night diving for sea cucumbers near Halong Bay. There have been other cases documented in Okinawa.