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".

[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.

This name is used in Thailand for all members of the Betta genus, which share similar aggressive tendencies, rather than for any specific strain of the Siamese fighting fish.

[18][19] According to Witte and Schmidt (1992), Betta splendens is native to Southeast Asia, including the northern Malay Peninsula, central and eastern Thailand, Kampuchea (Cambodia), and southern Vietnam.

[21] Wherever they are found, Betta splendens generally inhabit shallow bodies of water with abundant vegetation, including marshes, floodplains, and paddy fields.

[1] The historic prevalence of rice farming across Southeast Asia, which provided an ideal habitat for bettas, led to their discovery and subsequent domestication by humans.

[20] The combination of shallow water and high air temperature causes gases to rapidly evaporate, leading to a significant deficit of oxygen in the betta's natural habitat.

Subsequently, bettas can live and even thrive in harsher environments than other freshwater fish, which in turn leaves them with fewer natural predators and competitors.

[22] Consequently, Siamese fighting fish are highly adaptable and durable, able to tolerate a variety of harsh or toxic environments; this accounts for their popularity as pets, as well as their ability to successfully colonize bodies of water all over the world.

[1] In the wild, betta habitats are threatened by chemical and agricultural run off, in addition to the contamination of human medication residue into aquatic ecosystems from the sewage system.

Due to their short digestive tracts—a characteristic of most carnivores—bettas have difficulty processing carbohydrates such as corn and wheat, which are commonly used as fillers in many commercial fish foods.

[29] Bettas are susceptible to overfeeding, which can lead to obesity, constipation, swim bladder disease, and other health problems; excessive food may also pollute the water.

[8] Some people in Malaysia and Thailand are known to have collected wild bettas at least by the 19th century, observing their aggressive nature and pitting them against each other in gambling matches akin to cockfights.

In 1909, British ichthyologist Charles Tate Regan found there was a related species already named Macropodus pugnax, and thus renamed the domesticated Siamese fighting fish, Betta splendens, or "splendid fighter".

[citation needed] Betta splendens first entered the Western aquarium trade in the late 19th century; the earliest known arrival is 1874 in France, when French aquaria expert and ichthyologist Pierre Carbonnier began importing and breeding several specimens.

Fighting fish were also present in Australia by 1904, based on an article written by British-born zoologist Edgar Ravenswood Waite and published by the Australian Museum in Sydney.

[34] Due to their labyrinth organ, bettas can endure low oxygen levels, but cannot survive for long in unmaintained aquaria, as poor water quality makes all tropical fish more susceptible to diseases like fin rot,[35] or scale loss.

[citation needed] Although male bettas are solitary and aggressive towards one another, they can generally cohabit with many types of fish and invertebrates if there is adequate space and hiding places.

[citation needed] Bettas are fairly intelligent and inquisitive, and thus require stimulation; otherwise they can become bored and depressed, leading to lethargy and a weaker immune system.

[37] Decorations such as silk or live plants, rocks, caves, driftwood, and other ornaments provide crucial enrichment—provided they do not have rough textures or jagged edges, which can damage their delicate fins.

Their tannins allegedly confer several health benefits, including treating certain ailments like fin rot and bladder disease, and stabilising the pH of the water.

[39] A larger tank with proper filtration, regular maintenance, and an abundance of decor and hiding spaces, along with a rich, protein-based diet, increases the likelihood of a long lifespan.

Breeders have also developed different colour patterns such as marble and butterfly, as well as metallic shades like copper, gold, or platinum, which were obtained by crossing B. splendens to other Betta species).

They may set up a territory centered on a plant or rocky alcove, sometimes becoming highly possessive of it and aggressive toward trespassing rivals; consequently, bettas, if housed with other fish, require at least 45 litres (about 10 gallons).

[55] An observational study examined a group of female Siamese fighting fish over a period of two weeks, during which time they were recorded attacking, flaring, and biting food.

Similarly, researchers have found that when pairs of male Siamese fighting fish were kept together in the same tank for a three-day period, aggressive behaviour was most prevalent during the mornings of the first two days of their cohabitation.

[61] Siamese fighting fish are popular models for studying the neurological and physiological impact of certain chemicals, such as hormones, since their aggression is the result of cell signalling and possibly genes.

Later experiments confirmed the presence of genetic variation in hatchery stocks in Thailand, with low average numbers of alleles per locus and high heterozygosity rates.

As not only a source of revenue for the country and being a symbol of cultural significance, betta fish breeders have become a focal point of the government's assistance as they lack the capital and resources when wanting to expand their businesses.