Silver halfbeak (Dermogenys pusilla)

Silver halfbeak (Dermogenys pusilla) is a species of fish belonging to the family Zenarchopteridae. Found in freshwater and brackish environments, these small, slender, viviparous fish are characterized by an elongated lower jaw. Their coloration varies depending on their geographic location. They are aggressive feeders at the water's surface, preying on various small invertebrates, including crustaceans and insect larvae.

D. pusilla reproduces by giving birth to live young; a female can produce approximately 20 offspring after a gestation period of about one month. When the fish opens its mouth, its upper jaw lifts upward. This species exhibits sexual dimorphism.

Females are larger than males, reaching a length of 7 cm, while males grow up to 5.5 cm and typically feature red or yellow patches on their dorsal fins and jaws. Males often engage in combat with one another by locking their jaws—a behavior that can last for up to 30 minutes.

A male that loses a fight will quickly break away and swim off; consequently, these encounters rarely result in serious injury to either party. These fish are widely traded for the aquarium hobby, sold under the names "silver halfbeak" or "golden halfbeak," depending on their body coloration.

The species was first described as Dermogenys pusillus by Heinrich Kuhl and Johan Coenraad van Hasselt in 1823, with the type locality in Bogor, Java. The name was later adjusted to its feminine form.

TAXON

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Actinopterygii
Superorder: Acanthomorpha
Order: Beloniformes
Family: Zenarchopteridae
Genus: Dermogenys Kuhl & van Hasselt (1823)
Species: Dermogenys pusilla Kuhl & van Hasselt (1823)

SYNONYMS

Hemiramphus fluviatilis Bleeker (1850)

VERNACULAR NAME

Chinese (simplified): 皮颏鱵
Czech: Polozobánka malajská
English: Silver halfbeak, Wrestling halfbeak, Freshwater halfbeak, Malayan halfbeak, Half beak, Halfbeak
Indonesian: Cucut tawar, Julung, Julung-julung
Java: Cucut, Julung, Julung-julung
Malaysia: Jolong sungai, Menyulong, Menyulung, Jolong-jolong
Polish: Półdzióbek karłowaty
Russian: Бойцовый полурыл
Spanish: Golden halfbeak, Golden halfbeak

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