Wrestling halfbeak

The wrestling halfbeak (Dermogenys pusilla) also known as Malayan halfbeak is a species of viviparous halfbeak native to the fresh and brackish waters of rivers and coastal regions in South-East Asia, in Singapore, Thailand, Indonesia, Thailand, Malaysia, Borneo and Sumatra.[1][2] It is a small, slender, livebearing fish, with the elongated lower jaw characteristic of its family. The colour of this species varies, depending on where the specimen is found.[3] It is the type species of the genus Dermogenys.[4]

Wrestling halfbeak
Wrestling halfbeaks in an aquarium
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Beloniformes
Family: Zenarchopteridae
Genus: Dermogenys
Species:
D. pusilla
Binomial name
Dermogenys pusilla
Synonyms[1]

Hemiramphus fluviatilis Bleeker, 1850

Wrestling halfbeaks are surface-feeding fish and feed on a variety of small invertebrates including crustaceans and insect larvae, but especially mosquito larvae and flying insects that have fallen onto the surface of the water.[5] As with all halfbeaks, the upper jaw lifts upwards when the fish is opening its mouth. Wrestling halfbeaks are livebearing fish, the females giving birth to around twenty offspring after a gestation period of about a month.[6][7][8]

Wrestling halfbeaks are sexually dimorphic. The females are larger than the males and grow up to 7 cm (3 in) long; males only reach about 5.5 cm (2.2 in) and typically has red or yellow patches on the dorsal fin and the beak.[9][10] The males of wrestling halfbeaks will fight among themselves by locking jaws, hence their name, for up to thirty minutes.

This species was described as Dermogenys pusillus by Heinrich Kuhl and Johan Coenraad van Hasselt in 1823 with the type locality given as Bogor, Java, the name was subsequently amended to the feminine form.[11]

Fish fighting

In the wild, and in large aquaria, the weaker male will quickly disengage and swim away, and fights therefore rarely result in serious injury to either party. However, in their native range, local people sometimes use wrestling halfbeaks as fighting fish for betting purposes (like fighting cocks or siamese fighting fish).[12][13]

Wrestling halfbeaks in aquaria

Wrestling halfbeaks, as well as other species in the genus Dermogenys, are quite widely traded as aquarium fish, sometimes under the "silver halfbeak" or "golden halfbeak" names, depending on the colouration of the fish. As with all freshwater halfbeaks, these fish are sensitive to sudden changes in pH and hardness, but they are otherwise adaptable, and can be maintained in anything from soft and acid freshwater through to slightly brackish water.[14][15] When first introduced into the aquarium, wrestling halfbeaks are nervous fish that tend to be timid. They may swim frantically if suddenly frightened, even crashing into the walls. However, once they are used to their surroundings, they become lively, easy to care for fish.[16][17]

See also

References
  1. Froese, Rainer and Pauly, Daniel, eds. (2019). "Dermogenys pusilla" in FishBase. April 2019 version.
  2. "Dermogenys pusilla". Integrated Taxonomic Information System. Retrieved 19 March 2006.
  3. Schäfer F & M. Kemkes: All Livebearers and Halfbeaks, Aqualog 1998, ISBN 3-931702-77-4
  4. Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Dermogenys". Catalog of Fishes. California Academy of Sciences. Retrieved 23 August 2019.
  5. "Pygmy Halfbeak". Archived from the original on 2006-05-07. Retrieved 2006-09-03.
  6. Meisner, A & Burns, J: Viviparity in the Halfbeak Genera Dermogenys and Nomorhamphus (Teleostei: Hemiramphidae). Journal of Morphology 234, pp 295-317, 1997
  7. "Keeping & Breeding Halfbeaks". Retrieved 2006-09-03.
  8. Earl Blewett. "Dermogenys pusillus - The Wrestling Halfbeak Livebearer" (PDF). Retrieved 2006-09-03.
  9. Riehl R. & Baensch H: Aquarium Atlas (vol. 1), Voyageur Press, 1996, ISBN 3-88244-050-3
  10. Riehl R. & Baensch H: Aquarium Atlas (vol. 2), Microcosm Ltd, 1997, ISBN 1-890087-06-8
  11. Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Dermogenys pusillus". Catalog of Fishes. California Academy of Sciences. Retrieved 24 August 2019.
  12. "Freshwater Fishes and the Singaporean". Retrieved 2007-01-25.
  13. Sterba, G: Freshwater Fishes of the World, p. 609, Vista Books, 1962
  14. "Halfbeaks By Roger Fischer". Aqua News. January–February 1994. Archived from the original on 2006-05-15. Retrieved 2006-09-03.
  15. Monks N. (editor): Brackish Water Fishes, TFH 2006, ISBN 0-7938-0564-3
  16. Monks N: Straight to the point: the Beloniformes. Practical Fishkeeping, October 2005
  17. Monks N: Life at the Top. Tropical Fish Hobbyist, November 2006
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