{{Short description|Species of fish}} {{Speciesbox | image = Female Dermogenys sumatrana.jpeg | image_caption = Wrestling halfbeaks in an aquarium | status = DD | status_system = IUCN3.1 | status_ref = <ref name=IUCN>{{cite iucn |title=''Dermogenys pusilla'' |url= https://www.iucnredlist.org/species/90986075/90986088}}</ref> | taxon = Dermogenys pusilla | authority = Kuhl & van Hasselt, 1823 | synonyms = ''Hemiramphus fluviatilis'' <small>Bleeker, 1850</small> | synonyms_ref = <ref name = Fishbase/> }}
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, Indonesia, Thailand, Malaysia, Borneo and Sumatra.<ref name = Fishbase>{{FishBase|Dermogenys|pusilla|year=2019|month=April}}</ref><ref>{{ITIS |id=616690 |taxon=Dermogenys pusilla |accessdate=19 March 2006}}</ref> 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.<ref>Schäfer F & M. Kemkes: All Livebearers and Halfbeaks, Aqualog 1998, {{ISBN|3-931702-77-4}}</ref> It is the type species of the genus ''Dermogenys''.<ref name = CofFG>{{Cof record|genid=1304|title=''Dermogenys''|access-date=23 August 2019}}</ref>
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.<ref>{{cite web|url=http://www.ecologyasia.com/verts/fresh-fishes/pygmy-halfbeak.htm|title=Pygmy Halfbeak|accessdate=2006-09-03 |archiveurl = https://web.archive.org/web/20060507201357/http://www.ecologyasia.com/verts/fresh-fishes/pygmy-halfbeak.htm <!-- Bot retrieved archive --> |archivedate = 2006-05-07}}</ref> 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.<ref>Meisner, A & Burns, J: Viviparity in the Halfbeak Genera ''Dermogenys'' and ''Nomorhamphus'' (Teleostei: Hemiramphidae). Journal of Morphology 234, pp 295–317, 1997</ref><ref name="keepnbreed">{{cite web|url=http://homepage.mac.com/nmonks/aquaria/halfbeakbreeding.html|title=Keeping & Breeding Halfbeaks|accessdate=2006-09-03|archive-date=2008-01-28|archive-url=https://web.archive.org/web/20080128191930/http://homepage.mac.com/nmonks/aquaria/halfbeakbreeding.html|url-status=dead}}</ref><ref>{{cite web|url=http://okcaa.org/articles/Blewett%20Dermogenys%20pusillus.pdf#search=%22breeding%20dermogenys%20pdf%22|title=Dermogenys pusillus - The Wrestling Halfbeak Livebearer|author=Earl Blewett|accessdate=2006-09-03|archive-date=2009-12-29|archive-url=https://web.archive.org/web/20091229133638/http://okcaa.org/articles/Blewett%20Dermogenys%20pusillus.pdf#search=%22breeding%20dermogenys%20pdf%22|url-status=dead}}</ref>
Wrestling halfbeaks are sexually dimorphic. The females are larger than the males and grow up to {{convert|7|cm|in|round=0.5|abbr=on}} long; males only reach about {{convert|5.5|cm|in|abbr=on}} and typically has red or yellow patches on the dorsal fin and the beak.<ref>Riehl R. & Baensch H: Aquarium Atlas (vol. 1), Voyageur Press, 1996, {{ISBN|3-88244-050-3}}</ref><ref>Riehl R. & Baensch H: Aquarium Atlas (vol. 2), Microcosm Ltd, 1997, {{ISBN|1-890087-06-8}}</ref> 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.<ref name = CofF>{{Cof record|spid=13933|title=''Dermogenys pusillus''|access-date=24 August 2019}}</ref>
==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).<ref>{{cite web|url=http://habitatnews.nus.edu.sg/guidebooks/freshfish/text/105.htm|title=Freshwater Fishes and the Singaporean|accessdate=2007-01-25|archive-date=2007-02-05|archive-url=https://web.archive.org/web/20070205042430/http://habitatnews.nus.edu.sg/guidebooks/freshfish/text/105.htm|url-status=dead}}</ref><ref>Sterba, G: Freshwater Fishes of the World, p. 609, Vista Books, 1962</ref>
==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.<ref>{{cite web|url=http://www.mn-aquarium.org/masart23.htm|title=Halfbeaks By Roger Fischer|date=January–February 1994|publisher=Aqua News|accessdate=2006-09-03 |archiveurl = https://web.archive.org/web/20060515214402/http://www.mn-aquarium.org/masart23.htm <!-- Bot retrieved archive --> |archivedate = 2006-05-15}}</ref><ref>Monks N. (editor): Brackish Water Fishes, TFH 2006, {{ISBN|0-7938-0564-3}}</ref> 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.<ref>Monks N: Straight to the point: the Beloniformes. Practical Fishkeeping, October 2005</ref><ref>Monks N: Life at the Top. Tropical Fish Hobbyist, November 2006</ref>
==See also==
* Halfbeak * Live-bearing aquarium fish
== References == <!-- ---------------------------------------------------------- See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a discussion of different citation methods and how to generate footnotes using the <ref>, </ref> and <reference /> tags ----------------------------------------------------------- --> {{Reflist|2}}
==External links== {{Commonscatinline}}
{{Taxonbar|from=Q1570562}}
Wrestling Category:Live-bearing fish Category:Viviparous fish Category:Fishkeeping Category:Fish of Bangladesh Category:Taxa named by Johan Conrad van Hasselt