Siamese fighting fish

Siamese fighting fish
Halfmoon male
Conservation status
Vulnerable  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Anabantiformes
Family:	Osphronemidae
Genus:	Betta
Species:	B. splendens
Binomial name
Betta splendens Regan, 1910

The Siamese fighting fish (Betta splendens), commonly known as the betta,^[2] is a freshwater fish native to Southeast Asia, namely Cambodia, Laos, Myanmar, Malaysia, Indonesia, Thailand, and Vietnam.^[3][4] It is one of 76 species of the genus Betta, but the only one eponymously called "betta", owing to its global popularity as a pet; Betta splendens are among the most popular aquarium fish in the world, due to their diverse and colorful morphology and relatively low maintenance.^[5][6]

Siamese fighting fish are endemic to the central plain of Thailand, where they were first domesticated at least 1,000 years ago, among the longest of any fish.^[6][7][8] They were initially bred for aggression and subject to gambling matches akin to cockfighting. Bettas became known outside Thailand through King Rama III (1788–1851), who is said to have given some to Theodore Cantor, a Danish physician, zoologist, and botanist.^{[7][failed verification]} They first appeared in the West in the late 19th century, and within decades became popular as ornamental fish. B. splendens long history of selective breeding has produced a wide variety of coloration and finnage, earning it the moniker, "designer fish of the aquatic world".^[9]

Bettas are well known for being highly territorial, with males prone to attacking each other if housed in the same tank; without a means of escape, this will usually result in the death of one or both fish. Female bettas can also become territorial towards one another in confined spaces.^[10] Bettas are exceptionally tolerant of low oxygen levels and poor water quality, owing to their special labyrinth organ, a characteristic unique to the suborder Anabantoidei that allows for the intake of surface air.^[11]

In addition to its worldwide popularity, the Siamese fighting fish is the national aquatic animal of Thailand,^[12][13] which remains the primary breeder and exporter of bettas for the global aquarium market. Despite their abundance as pets, B. splendens is listed as "vulnerable" by the IUCN, due to increasing pollution and habitat destruction. Efforts are being made to support betta fish breeders in Thailand as a result of their popularity as pets, cultural significance, and need for conservation.