| Freshwater Garfish | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Beloniformes |
| Family: | Belonidae |
| Genus: | Xenentodon |
| Species: | X. cancila |
| Binomial name | |
| Xenentodon cancila (Hamilton, 1822) |
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| Synonyms | |
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The freshwater garfish, Xenentodon cancila is the sole member of its genus. It is found primarily in freshwater habitats,[1] though it is sometimes found in brackish water and the sea.[1] It is most common in rivers, but may also be found ponds, canals, and other freshwater habitats.[1] It is the only member of the genus Xenentodon.
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As a reasonably popular aquarium fish Xenentodon cancila, has been traded under a variety of common names, including needlefish,[2] silver needlefish,[3] Asian freshwater needlefish,[2] needlenose halfbeak,[4] freshwater gar,[4] and numerous others. While belonging to the same family as the marine needlefish known in Europe as gar or garpike, Belone belone,[5] these fish are of course much more distantly related to other fishes sometimes called gars (such as the North American Lepisosteidae and South American pike characins).[4]
The freshwater garfish is widely distributed across South and Southeast Asia from India and Sri Lanka to the Malaysian Peninsula.[3]
In common with other needlefish, this species has an elongate body with long, beak-like jaws filled with teeth.[5] The dorsal and anal fins are positioned far back along the body close to the tail.[5] The body is silvery-green, darker above and lighter below with a dark band running horizontally along the flank.[1] Slight sexual dimorphism exists, the male fish often having anal and dorsal fins with a black edge.[3][5]
While aquarium books tend to describe this fish as a predator that eats animals such as fish and frogs,[3] its natural diet appears to consist almost entirely of crustaceans.[3]
This species is oviparous.[3] In aquaria at least, spawning takes place in the morning,[3] with small numbers of eggs being deposited among plants.[3] The eggs are about 3.5 mm in diameter and are attached to plant leaves with sticky threads about 20 mm long.[3] The eggs take ten days to hatch, at which point the fry are almost 12 mm long.[3] At this point they will eat small live foods including week-old labyrinth fish.[3]
Freshwater needlefish support minor fisheries and are also traded as aquarium fish.[1]
The freshwater garfish is one of a handful of needlefish species kept in public and home aquaria.[5] It has been kept by European aquarists since 1910,[5] and was first bred in captivity at the Biological Station Wilhelminenberg, Austria in 1963.[3] Xenentodon cancila is generally considered quite a difficult species to maintain because of its large size, nervous behaviour, and preference for live foods.[2] Alongside misunderstandings of the natural diet of these fish,[6] there has been confusion over the optimal water conditions required by this species when kept in home aquaria, with the addition of salt to the water often being recommended.[4] In fact these fish do perfectly well in freshwater aquaria.[6]
Xenentodon cancila has been said to be able to launch itself out of the water with such force that it can kill a human, though some ichthyologists say that this is unlikely.[1] They are certainly capable of biting.[1]