Every species

Betta persephone is a small bubble-nesting labyrinth fish that appears to be endemic to southwestern Johor state, Peninsular Malaysia. A blackish member of the mostly red B. coccina group, it is most similar to B. miniopinna but has a deeper body and blackish to dull reddish pelvic fins. It inhabits peat swamp forests and associated streams, where the pH can be as low as 3.0 or 4.0.

Betta pi is a large paternal mouthbrooding labyrinth fish from peat swamps in southern Thailand and the states of Kelantan and Terengganu, Malaysia. A member of the B. waseri group, it is named for the dark marking on the throat shaped like the Greek letter pi. It is not among the more aggressive members of the genus and can be maintained in a pair or group.

The spotted betta, Betta picta, is a small paternal mouthbrooding labyrinth fish known only from Java, Indonesia. It lends its name to the B. picta complex and has iridescent yellow-gold opercle scales. It is usually found in quiet margins and still pools of clear, flowing hill streams, but has also been collected from roadside ditches and water tanks.

Betta pinguis is a paternal mouthbrooding labyrinth fish known only from the middle and upper Kapuas watershed in West Kalimantan, Indonesian Borneo. A member of the B. akarensis group, it has a relatively stocky body and dense dark markings on the opercle below the postorbital stripe. The type specimens came from a small, slightly tannin-stained stream in degraded forest, where B. dimidiata and B. enisae also occur.

Betta prima is a paternal mouthbrooding labyrinth fish from south-eastern Thailand and the Mekong basin in Cambodia and Laos. Before its description it was widely misidentified as B. pugnax or B. taeniata, and not all authors place it in the B. pugnax complex. It inhabits clear-water forest swamps and streams that can be still or swift, sheltering among marginal roots, leaf litter and vegetation.

Betta pugnax is a paternal mouthbrooding labyrinth fish from much of Peninsular Malaysia and Singapore, described from Penang. It lends its name to the B. pugnax complex. Populations inhabit shallow, flowing clear-water hill streams as well as stiller forest swamps. It is not among the more aggressive members of the genus and can be maintained in a pair or group.

Betta pulchra is a mouthbrooding labyrinth fish from southwestern Johor in southern Peninsular Malaysia. It is restricted to remnant blackwater habitats in heavily-disturbed former peat swamp forest cleared for oil palm, pineapple and rubber plantations, where it lives among the overhanging marginal vegetation of irrigation canals at a pH of 3.9 to 4.2. A member of the B. pugnax complex, it has a chin bar, transverse bars in the caudal fin and iridescent green scales on the opercle.

Betta raja is a mouthbrooding labyrinth fish endemic to Sumatra, Indonesia, found in the Batang Hari and Indragiri river basins. Before its description it was widely misidentified as Betta fusca. It lives in lowland forest swamps with both clear and black water, and mature males of this B. pugnax complex member have very long pelvic fins and black marginal bands on the anal and lower caudal fins. Populations from different localities should be labelled as such to preserve pure bloodlines.

Betta renata is a mouthbrooding labyrinth fish from forest peat swamps in Jambi, South Sumatra and Riau provinces on Sumatra, Indonesia. A member of the B. waseri group, it is most easily identified by a clearly-defined dark, kidney-shaped blotch on the throat that is always separate from the dark lower jaw. Its blackwater habitats can have a pH as low as 3.0 or 4.0, and at certain times of year the fish may be forced to survive in moist leaf litter for several weeks.

Betta rubra is a small labyrinth fish from northwestern Sumatra, Indonesia, known from the Singkil area of Aceh and around Sibolga in North Sumatra. Conflict in the region meant it was known only from the type specimens for around 100 years, and it began to appear in the hobby in early 2007. It is typically exported mixed with the similar-looking B. dennisyongi and may have been hybridised with it. The two are told apart mainly by the opercle pattern and the width of the triangular black mark below the eye.

Betta rutilans is a small, deep red labyrinth fish from peat swamps near Anjungan in West Kalimantan, Borneo, Indonesia. Known in the hobby as B. sp. 'Anjungan' before its description, it belongs to the B. coccina group, whose members can be hard to identify because their patterning is similar and confusingly variable. B. rutilans has a uniformly deep red body with no midlateral blotch. A bubble-nester, it lives in blackwater streams where the pH can be as low as 3.0 or 4.0.

Betta siamorientalis is a small bubble-nesting labyrinth fish from eastern Thailand, western Cambodia and Vietnam. It lives among submerged vegetation in marshes, flooded fields and rice paddies. Before its description in 2012 it was considered a colour form of B. imbellis known as 'black imbellis', and it has also been confused with B. splendens, but DNA analysis showed it to be distinct. Males have a dark brown to black body and a black opercle with two reddish vertical bars.

Betta simorum is a slender bubble-nesting labyrinth fish from Sumatra and the Kapuas River system in West Kalimantan, Borneo, Indonesia. Growing to around 90 mm SL, it inhabits heavily-vegetated forest peat swamps and blackwater streams. It shares the B. bellica group with B. bellica, from which it differs in its slanted head with a concave profile behind the eye. Populations are often labelled by locality, such as Rantau Panjang or Sungai Bengkwan, to preserve pure bloodlines.

Betta simplex is a mouthbrooding labyrinth fish known only from Krabi province in southern (peninsular) Thailand. Its habitats lie in a karstic area of limestone sinkholes with clear, neutral to alkaline water at pH 7.0 to 7.4. It is most abundant in a small ditch draining the pools that often dries out, leaving some fish in shallow remnant pools. A population from near Ao Luek has appeared in the hobby as B. simplex 'type 2'.

The emerald betta, Betta smaragdina, is a bubble-nesting labyrinth fish from the Khorat Plateau in eastern Thailand and Mekong tributaries in Laos. It inhabits still and sluggish waters such as rice paddies, swamps and roadside ditches. It has been line-bred for aggression in eastern Thailand, and selectively bred and hybridised for the ornamental trade into colour forms that do not occur naturally. Wild populations vary in the extent of red or green patterning and are often labelled by locality.

Betta sp. 'Antuta/Bulungan' is an undescribed mouthbrooding labyrinth fish from Bulungan Regency in East Kalimantan, northern Indonesian Borneo. It appears to be a member of the B. unimaculata complex, and its habitat is thought to be flowing highland streams. Adult size is unconfirmed but likely to be 90 to 100 mm. Relatively peaceful, it can be kept in a group in a tank of sufficient size with plenty of hiding places.

Betta spilotogena is a mouthbrooding labyrinth fish from Bintan and Singkep islands in the Riau Islands province of Indonesia. It inhabits shaded freshwater swamps and streams with clear or lightly tannin-stained water less than a metre deep, alongside B. edithae, B. miniopinna and B. fusca. A member of the B. waseri group, it has a single dark, pear-shaped blotch on the throat that is not joined to the black lower lip.

The Siamese fighting fish, Betta splendens, is a labyrinth fish from central Thailand, native to rice paddies, swamps, ditches and other still waters. The wild form is rarely seen in the hobby, but countless ornamental strains exist that vary tremendously in colour, finnage and quality. Its care requirements and disposition mean it is best kept alone, and it is not recommended for the standard community aquarium.

Betta stigmosa is a mouthbrooding labyrinth fish from forest hill streams in Terengganu state, Peninsular Malaysia. The type specimens came from a stream draining into the Sekayu waterfalls near Kuala Berang, and it has since been recorded around 150 km to the south. Its streams carry clear, flowing water over rocks, gravel and leaf litter. In this member of the B. pugnax complex both sexes have transverse bars in the dorsal, anal and caudal fins.

Betta taeniata is a mouthbrooding labyrinth fish endemic to Borneo, known from southern Sarawak in Malaysia and northern West Kalimantan in Indonesia. It is usually associated with clear, flowing hill streams, where it lives in quiet marginal zones and still pools among leaf litter and gravel. A member of the B. picta group, it has a yellowish body and fins and a blackish head. Populations such as Sri Aman, Serian and Kapuas are often labelled by locality to preserve pure bloodlines.