Combattant

The Betta is part of the labyrinthid family (currently Osphronemidae), meaning it has a labyrinth that allows it to come breathe air at the surface (this is why it lives in oxygen-poor waters). It is a very territorial fish, which earned it the name Siamese Fighting Fish or simply Betta. Males can be very bellicose toward each other and engage in violent fights, potentially leading to the death of the loser. This is due solely to selection by humans: current bettas have a serotonin deficit, genetically fixed through breeding for millennia (approximately 6,000 years that they have been raised in large bowls, selecting the most beautiful and especially the most aggressive). Because of this, they are sometimes very difficult to breed, as males are capable of killing their females as well, confusing parading to impress with attacking to kill. Humans have condemned it to solitude; that said, there are increasingly Betta splendens with more flexible behavior, capable of living with small gregarious fish with similar parameters, the fighting criterion being progressively abandoned. Females are generally duller, although nowadays more and more colored females are encountered, highly prized by breeding selection. Their fins, however, remain shorter, although some selected females are starting to have veil fins sometimes almost as long as those of young males. There is a form of short-finned male betta called Plakat. A novice may not distinguish between a short-finned male and a female; the major difference to distinguish a short-finned male from a female, regardless of its original form, is that a plakat male has a very visible point at the end of its ventral fin (also called anal fin), whereas in females, generally, it is much more rounded.

In the wild, the Betta is a species that measures on average 4 cm in length and more rarely up to 6.5 cm. The wild form has short fins and a brownish color, with only a few traces of green or red. Originally, when they chase an opponent to protect their territory, they are not fish that fight to the death. The wild variety merely intimidates by parading to impress the conspecific and make it flee, unlike animals selected for fighting by humans, which can sometimes even kill a female.

Siamese fighting fish are endemic to Thailand, particularly the Chao Phraya River basin which extends over a large part of the country's center; however, their natural range extends throughout the Mekong Basin, including Cambodia, Laos, and Vietnam. They are also found throughout the neighboring Malay Peninsula and in adjacent parts of Sumatra, probably due to human introduction. The worldwide popularity of the betta has led to its release and establishment in similar tropical areas, notably southeast Australia, Brazil, Colombia, Dominican Republic, southeast United States, and Singapore. Wherever they are found, Siamese fighting fish generally inhabit shallow bodies of water with abundant vegetation, including marshes, floodplains, and rice paddies. The historical prevalence of rice cultivation in Southeast Asia, which provided ideal habitat for bettas, led to their discovery and subsequent domestication by humans. The combination of shallow water and high air temperature causes rapid evaporation of gases, resulting in a significant oxygen deficit in the betta's natural habitat. This environment probably led to the evolution of the lung-like labyrinth organ, which allows Siamese fighting fish - like all members of the suborder Anabantoidei - to breathe directly from the air. Subsequently, bettas can live and even thrive in more challenging environments than other freshwater fish, which in turn leaves them with fewer natural predators and competitors. The tropical climate of the betta's natural habitat is characterized by sudden and extreme fluctuations in water availability, chemistry, and temperature. Water pH can range from slightly acidic (pH 6.9) to highly alkaline (pH 8.2), while air temperatures drop as low as 15°C (59°F) and rise to 40°C (100°F). Consequently, Siamese fighting fish are highly adaptable and hardy, capable of tolerating a variety of difficult or toxic environments; this explains their popularity as pets, as well as their ability to successfully colonize bodies of water around the world. Wild bettas prefer to live in bodies of water teeming with aquatic vegetation and surface foliage, such as dead leaves and water lilies. The abundance of plants provides security against predators and a buffer between aggressive males, which coexist by claiming dense sections of plants as territory. Such vegetation also provides protection to females during spawning and to fry during their earliest and most vulnerable stages.

In its natural environment, the Betta is a carnivorous predator; it feeds on small living prey, such as daphnia, artemia, banana worms, and if bought in a pet store as flakes or pellets. In captivity, the latter must follow a meat-based diet.