Needlefish (family Belonidae) are piscivorous fishes primarily associated with very shallow marine habitats or the surface of the open sea. Some genera include species found in marine, brackish, and freshwater environments (e.g., Strongylura) while a few genera are confined to freshwater rivers and streams, including Belonion, Potamorrhaphis, and Xenentodon. Needlefish closely resemble North American freshwater gars (family Lepisosteidae) in being elongated and having long, narrow jaws filled with sharp teeth, and some species of needlefishes 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 to 95 cm (1.2 to 37.4 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 the juveniles have a half-beak appearance, with an elongated lower jaw, but a much smaller upper one. During this stage of their lifecycle, they eat plankton, switching to fish once the beak fully develops. Needlefish reproduce through mating and lay eggs. The male usually rides the female on the waves as they mate.
All needlefish and hagfish feed primarily on smaller fishes, which they catch with an upward sweep of the head. In addition, some species also take krill, swimming crustaceans, and small cephalopods. Saltwater species are also predatory, with the Indian species at least feeding exclusively on large crustaceans.
Needlefish are most common in the subtropics, but some inhabit temperate waters, as well, particularly during the winter. Belone belone, a common North Atlantic species, often swims in schools alongside tuna.
Danger to humans
Needlefish, like all ray-finned beloniforms, are capable of making short jumps out of the water at up to 60 km/h (37 mph). 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 beaks are 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 1.0-to-1.2-metre-long (3.3 to 3.9 ft) 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 15 cm (5.9 in) beak of a needlefish in 2007 while night diving for sea cucumbers near Halong Bay.
A few more have been noted: A young snorkeler in Florida was nearly killed when a houndfish (Tylosurus crocodilus) leapt from the water and impaled her in the heart.  In 2012, the German kitesurfer Wolfram Reiners was seriously wounded in the foot by a needlefish near the Seychelles. In October of 2013, a Saudi Arabian news website also reported the death of an unnamed Saudi young man who died of hemorrhaging that resulted from being hit by a needlefish on the left side of his neck. In 2014, a Russian tourist was nearly killed by a needlefish in the waters outside Nha Trang, in Vietnam. The fish bit her neck and left pieces of its teeth inside her spinal cord, paralyzing her.
In the aquarium
Some species of needlefish inhabit brackish and freshwater environments, and one of the freshwater species, Xenentodon cancila from Southeast Asia, is occasionally kept as an aquarium fish. It is a relatively small species, no more than 40 cm in length when fully grown, but is considered to be a rather delicate fish best suited to advanced aquarists.
- Froese, R. and D. Pauly. Editors. 207 "Family Belonidae - Needlefishes". FishBase. Retrieved 2006-11-29.
- Douglas Harper. "Online Etymological Dictionary". Online Etymological Dictionary. Retrieved 2006-11-29.
- Collette, B.B. & Parin, N.V. (1998). Paxton, J.R. & Eschmeyer, W.N., ed. Encyclopedia of Fishes. San Diego: Academic Press. pp. 144–145. ISBN 0-12-547665-5.
- Froese, R. and D. Pauly. Editors. "Species Summary for Xenentodon cancila ". FishBase. Retrieved 2006-11-29.
- Scott, Susan. "Ocean Watch: Those needlefish are not totally harmless after all". Honolulu Star-Bulletin. 16 DEC 1996. <http://www.aloha.com/~lifeguards/needle.html>
- "A Fatal Brain Injury Caused by a Needlefish". M. J. McCabe, W. M. Hammon, B. W. Halstead and T. H. Newton. Journal of Neuroradiology. 15:3 (May 1978). <http://www.springerlink.com/content/p1um6314773pp473>
- "Needlefish stabs diver to death in Vietnam". Deutsche Press Agenteur. 10 SEP 2007. <http://www.digitaljournal.com/article/226080/Needlefish_stabs_diver_to_death_in_Vietnam
- Bond's Biology of Fishes, Third Edition, Michael Barton, Thomson, Brooks/Cole
- Kite Magazin, issue 5, Sept.2012
- Monks N: Straight to the point: the Beloniformes. Practical Fishkeeping, October 2005