Dermogenys

Dermogenys
Dermogenys sumatrana, pregnant female about 5 cm (2 in) long
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Beloniformes
Family:	Zenarchopteridae
Genus:	Dermogenys Kuhl & van Hasselt, 1823
Type species
Dermogenys pusillus Kuhl & van Hasselt, 1823

Dermogenys is a genus of viviparous halfbeaks. They are widely distributed in fresh and brackish water in South and Southeast Asia, ranging from India to the Philippines and Greater Sundas. They are all viviparous, producing small clutches of up to 30 fry that closely resemble the adults, except they are much smaller, around 1–1.5 cm (0.4–0.6 in) in length. Adults are typically around 6–7 cm (2.4–2.8 in) in length, with females being slightly larger than males. Males tend to be more brightly coloured and are well known for being aggressive towards one another. The wrestling halfbeak, D. pusilla, is widely used in Asia as fighting animals upon which wagers are placed (see Siamese fighting fish). Both sexes have lower jaws (mandibles) that are much longer than the upper ones, and from this comes the "halfbeak" name.

Dermogenys feed extensively on small insects, either in the form of aquatic larvae or as flying insects that have fallen onto the surface of the water. They are important predators on insects such as mosquitoes, so play a role in controlling malaria.