Betta is the genus of wild fighting fish and mouthbrooding bettas, part of the gourami family Osphronemidae and, like other anabantoids, equipped with a labyrinth organ that lets them gulp air at the surface, an adaptation to the low-oxygen, often acidic blackwater and peat-swamp streams of Southeast Asia. The atlas covers 78 species, from 1–5.5 in, distributed across Indonesia, Malaysia, Thailand, Cambodia, Laos, Vietnam, Brunei Darussalam, and Singapore. The genus splits along a fundamental behavioural line: bubble-nest builders, which guard eggs in a foam nest at the surface, and mouthbrooders, in which a parent carries the eggs in its jaws through incubation.
Wild bettas draw a dedicated specialist following distinct from the domesticated Siamese fighting fish familiar to most aquarists. Species such as the Brunei Beauty (Betta macrostoma), Crescent Betta (B. imbellis), Snakehead Betta (B. channoides), and the mouthbrooding Whiteseam fighter (B. albimarginata) and Green Throat Mouthbrooder (B. chloropharynx) are kept by hobbyists in soft, acidic, tannin-stained water that mimics their native streams, usually in quiet species tanks rather than busy communities, since most wild Betta are shy and sensitive to bolder tankmates.
Conservation concern is severe and widespread across the genus: the atlas tally includes 11 Critically Endangered, 17 Endangered, and 11 Vulnerable species, and 41 of the 78, more than half, carry a CARES conservation priority flag. Most wild bettas are narrow-range specialists of peat-swamp forest and small forest streams in Borneo, Sumatra, and mainland Southeast Asia, habitats under heavy pressure from logging, drainage, and conversion to plantation agriculture, which puts single-catchment species at disproportionate risk.