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Betta

Genus of fish

Wikipedia contributorsAdapted for Fathomly · View authors
6 min read
Source updated July 14, 2026
Image credit is listed at the end of this article.

Betta (/ˈbɛtə/, BET-tə) is a large genus of small, active, often colorful, freshwater ray-finned fishes, in the gourami family (Osphronemidae). The best known Betta species is B. splendens, commonly known as the Siamese fighting fish and often kept as an aquarium pet.

01Characteristics

All Betta species are small fishes, but they vary considerably in size, ranging from under 2.5 cm (1 in) total length in B. chanoides to 14 cm (5.5 in) in the Akar betta (B. akarensis).

Bettas are anabantoids, which means they can breathe atmospheric air using a unique organ called the labyrinth. This accounts for their ability to thrive in low-oxygen water conditions that would kill most other fish, such as rice paddies, slow-moving streams, drainage ditches, and large puddles.

The bettas exhibit two kinds of spawning behaviour: some build bubble nests, such as B. splendens, while others are mouthbrooders, such as B. picta. The mouthbrooding species are sometimes called "pseudo bettas", and are sometimes speculated to have evolved from the nest-builders in an adaptation to their fast-moving stream habitats.

A phylogenetic study published in 2004 concluded tentatively that bubble-nesting was the ancestral condition in Betta, and that mouthbrooding has evolved on more than one occasion in the history of the genus. However, it was unable to establish a correlation with any of three habitat variables studied: whether a species was found in lowland or highland streams, whether it was found in peat swamp forests, and whether it was found in water with fast or slow currents. Mouthbrooding species tend to exhibit less sexual dimorphism, perhaps because they do not need to defend a territory as the bubble-nesters do.

Betta splendens, the Siamese fighting fish, is often referred to simply as a "betta" in the U.S.
Betta splendens, the Siamese fighting fish, is often referred to simply as a "betta" in the U.S.

02Name

Siamese fighting fish (B. splendens) are frequently sold in the United States simply as "bettas". As of 2017, around 73 species are classified within the genus Betta. A useful distinction is that, while the generic name Betta is italicized and capitalized, when used as a common name it is usually neither italicized nor capitalized. The common name of B. pugnax, for example, is thus Penang betta.

The name Betta (or betta) is pronounced /ˈbɛtə/; the first part is the same as the English word bet. The name is often pronounced /ˈbeɪtə/ in American English, and may be spelled with one 't'. The name of the genus is derived from the Malay term ikan betah ("persistent fish").

The vernacular name "plakat", often applied to the short-finned ornamental strains, derived from pla kad which means "fighting fish", is the Thai name for all members of the B. splendens species complex (All have aggressive tendencies in the wild and all are extensively line-bred for aggression in eastern Thailand). The Thai phrase is not restricted to one specific strain. The term "fighting fish" is generalized to all members of the B. splendens species complex, including the Siamese fighting fish.

03Diet

Wild Betta fish are hardy and eat almost any animal small enough to consume. This includes worms, larvae of mosquitoes or other insects, and smaller fish. Their natural environment is often resource-limited, so many Betta species are generalist feeders.

A pair of Betta smaragdina
A pair of Betta smaragdina

04Bettas as pets

Bettas are commonly kept as pet fish, especially Siamese fighting fish. Bettas are popular fish due to their color variety and ease to care for, although the males must be kept separated from other bettas.

05Conservation

While many Betta species are common and B. splendens is ubiquitous in the aquarium trade, other bettas are threatened. The IUCN Red List classifies several Betta species as Vulnerable. In addition, B. livida is Endangered, and B. miniopinna, B. persephone, and B. spilotogena are Critically Endangered.

The United Nations Environment Programme lists an unconfirmed species, Betta cf. tomi, as having become extinct in Singapore between 1970 and 1994. This likely refers to the extirpated Singaporean population of B. tomi, which continues to exist in the wild in Indonesia and Malaysia, as well as in captivity; the Red List classifies it as Vulnerable.

Male Betta tussyae
Male Betta tussyae

06Species

There are currently 78 recognized species in this genus. The currently described Betta species can be grouped into species complexes:

Watch videos about BettaExplainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “Betta”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

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