The freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 and brackish water halfbeak

Halfbeak

The halfbeaks are a geographically widespread and numerically abundant family of epipelagic fish inhabiting warm waters around the world. The family Hemiramphidae is divided into two subfamilies, the primarily marine Hemiramphinae and the freshwater or estuarine Zenarchopterinae...

s of the genus Dermogenys are widely distributed in South and Southeast Asia from India to Indonesia. They are all viviparous, producing small clutches of up to 30 fry that closely resemble the adults, except they are much smaller, around 10 to 15 mm in length. Dermogenys adults are typically around 60–70 mm 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

Wrestling halfbeak

The wrestling halfbeak, Dermogenys pusilla, also known as Malayan halfbeak is a member of the halfbeak family found in the fresh and brackish waters of rivers and coastal regions in South-East Asia, in Singapore, Thailand, Indonesia, Thailand, Malaysia, Borneo and Sumatra...

, Dermogenys pusilla, is widely used in Asia as fighting animals upon which wagers

Gambling

Gambling is the wagering of money or something of material value on an event with an uncertain outcome with the primary intent of winning additional money and/or material goods...

 are placed (see Siamese fighting fish

Siamese fighting fish

The Siamese fighting fish , also known as the betta , is a popular species of freshwater aquarium fish. The name of the genus is derived from ikan bettah, taken from a local dialect of Malay...

). Both sexes have lower jaws (mandibles) that are much longer than the upper ones, and from this comes the "halfbeak" name.

Dermogenys fish feed extensively on small insects, either in the form of aquatic larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e 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

Malaria

Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

.

See the article on halfbeak

Halfbeak

The halfbeaks are a geographically widespread and numerically abundant family of epipelagic fish inhabiting warm waters around the world. The family Hemiramphidae is divided into two subfamilies, the primarily marine Hemiramphinae and the freshwater or estuarine Zenarchopterinae...

s for details on the maintenance of these fish in home aquaria.

Reproduction

Dermogenys are live-bearing fish that practise internal fertilisation. The male is equipped with a gonopodium-like anal fin known as an andropodium that delivers sperm into the female. The gestation

Gestation

Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

 period is about one month. The exact mode of reproduction ranges from ovoviviparity through to viviparity (see section on reproduction in the halfbeak article). About ten embryos are developed at any one time, but at birth, these are fairly large (around 10 mm) compared with other fish of this size (Dermogenys adults are around 4–7 cm in length, depending on the species).

Species

Dermogenys weberi

Dermogenys weberi

Dermogenys weberi is a species of fish in the Hemiramphidae family. It is endemic to Indonesia.-Source:* Kottelat, M. 1996. . Downloaded on 4 August 2007....

Dermogenys megarramphus

Dermogenys megarramphus

Dermogenys megarramphus is a species of fish in the Hemiramphidae family. It is endemic to Indonesia.-Source:* Kottelat, M. 1996. . Downloaded on 4 August 2007....

Dermogenys bispina

Dermogenys brachynotopterus

Dermogenys bruneiensis

Dermogenys burmanica

Dermogenys collettei

Dermogenys montana

Dermogenys orientalis

Dermogenys palawanensis

Dermogenys pusilla

Dermogenys robertsi

Dermogenys siamensis

Dermogenys sumatrana

Dermogenys vogti