Taxonomy & naming
Betta compuncta was described by Kelvin K. P. Tan and Peter K. L. Ng in 2006 as a member of the unimaculata group, a clade of large, paternal mouthbrooding bettas distributed across Borneo and adjacent islands. The type locality is East Kalimantan (Kalimantan Timur) on the Indonesian part of Borneo. Eschmeyer's Catalog of Fishes recognises the valid name as Betta compuncta Tan & Ng, 2006; the species has not been moved from its original genus, so no parenthetical authority is used.
The unimaculata group takes its name from Betta unimaculata, the best-known species in the assemblage, and unites several large-bodied mouthbrooders that share a broadly similar body plan and reproductive strategy. Within the group B. compuncta is distinguished chiefly by its reticulated colour pattern — a character more strongly expressed in females than in males, which is an unusual reversal of the ornate-male norm found across most of the genus.
Morphology
Betta compuncta reaches up to approximately 2.5 in standard length, placing it among the larger members of the genus. The body is elongate and moderately compressed, typical of the unimaculata group, with a relatively large mouth — an adaptation common in paternal mouthbrooders that must carry and protect a clutch of eggs and early fry.
The defining colour character is a distinct black reticulated pattern overlying the body, best expressed in females. The reticulation consists of dark scale edges that create a net-like or punctuate appearance; it is from this pattern that the species receives its name. Fin-ray counts recorded from the original description include 28–30 anal-fin rays and 8–10 dorsal-fin rays. Like all bettas, B. compuncta possesses the labyrinth organ — a folded suprabranchial accessory breathing structure that allows it to extract oxygen directly from the air, a critical adaptation to the oxygen-depleted blackwaters it inhabits.
Habitat
Betta compuncta is endemic to East Kalimantan (Kalimantan Timur), the eastern Indonesian province of Borneo. Within that region it inhabits slow-flowing small streams set within swampy heath forest — the distinctive kerangas vegetation that grows on extremely nutrient-poor, white-sand soils. These habitats produce highly acidic blackwater: water chemistry recorded at B. compuncta localities falls in the range of pH 3.7–5.3, some of the most acidic conditions documented for any betta.
Heath-forest streams are stained dark by dissolved humic and tannic acids leaching from leaf litter and peat. Dissolved oxygen levels are low, which is why the labyrinth organ is so ecologically important; water temperatures in these lowland forest habitats are tropical but often cooler than open river systems under dense canopy. The streams are typically shallow, with marginal vegetation, submerged leaf litter, and fallen woody debris providing structure and cover. Deforestation and conversion of heath-forest peatlands to plantation agriculture represent the principal threats to the species' habitat.
Feeding
Like other members of the unimaculata group, Betta compuncta is a carnivore that feeds on small aquatic and terrestrial invertebrates in the wild. The slow, leafy streams it inhabits offer an assortment of insect larvae, small crustaceans, zooplankton, and insects that fall or land on the surface — the typical prey spectrum for a betta-sized predator in a forested stream.
In captivity, bettas of this group readily accept small live and frozen invertebrates: Daphnia, brine shrimp, bloodworm, and mosquito larvae are all readily taken. A diet weighted toward live and frozen foods keeps the fish in better condition and more likely to exhibit breeding behaviour than a flake-only regime. Because these are sit-and-wait ambush predators more than active pursuit hunters, feeding two to three times daily in modest portions suits them better than large infrequent meals.
Mating
Betta compuncta is a paternal mouthbrooder, the reproductive strategy that defines the unimaculata group. Courtship is protracted and involves extended displays by the male, including fin spreading and lateral posturing to assess and stimulate the female. A receptive pair engages in the characteristic embrace of the genus, in which the male wraps his body around the female to press eggs and sperm together; for mouthbrooding bettas these embraces are repeated in distinct episodes, with eggs released in small batches across several bouts rather than all at once.
Once fertilised, the eggs are taken up by the male — in mouthbrooding bettas it is the male who broods. The female is typically chased off at this point or departs voluntarily, and the male is left to incubate the clutch alone. Based on close relatives in the unimaculata group, incubation lasts approximately 10–14 days, during which the male eats nothing.
Breeding
During incubation the male holds the fertilised eggs in his buccal cavity, aerating them with gentle jaw movements and occasionally rolling them. He does not feed for the duration of the brooding period. After roughly 10–14 days — the timing varies with temperature — he releases free-swimming fry that are already relatively large and robust compared with the newly hatched larvae of bubble-nesting bettas.
In the aquarium, breeding B. compuncta and its unimaculata-group relatives requires close attention to water chemistry: very soft, highly acidic water in the pH 4.0–6.0 range and temperatures in the low-to-mid 20s Celsius are indicated by the species' wild habitat. A species-only or pair tank with dim lighting, abundant leaf litter or peat filtration, and minimal water movement replicates the calm heath-forest stream environment. The brooding male should not be disturbed; attempts to move him or excessive netting stress may cause him to swallow or spit the clutch prematurely. Released fry are large enough to accept baby brine shrimp and micro-worms from the start.
In the aquarium
Betta compuncta is an uncommon species in the hobby, available mainly through specialist breeders working with unimaculata-group bettas. It demands water conditions that replicate its native blackwater: pH below 6.0, very soft water, and warm temperatures around 75–82 °F. Peat filtration or alder cones and Indian almond leaves help achieve the tannin-rich, acidic chemistry the species requires; standard tap water with a neutral pH is unsuitable and will suppress breeding and stress the fish over time.
Being a labyrinth fish, it must have unobstructed access to the water surface to breathe air; a tight-fitting lid is equally important to prevent escapes and to keep a warm, humid air layer above the water — cold, dry air contacting the labyrinth organ can injure or kill the fish. A species tank or a very carefully chosen community of similarly small, non-aggressive blackwater inhabitants is strongly preferred; bettas of this group can be territorial with their own sex. Decor should include leaf litter, driftwood, and low-light plants. Betta compuncta is quiet, cryptic, and rewards patient observation — particularly during the brooding phase, when the male can be watched carrying the clutch.
Conservation
The IUCN Red List assessed Betta compuncta as Data Deficient (DD) as of 7 December 2018, reflecting the lack of quantitative population data rather than a known absence of threats. The species is a narrow endemic tied to heath-forest blackwater streams in East Kalimantan, a region that has experienced severe deforestation and peatland conversion for palm-oil and timber production. The habitat on which it depends — intact kerangas heath forest over acidic white-sand soils — is among the most threatened land-cover types in Borneo.
Data Deficient does not mean safe: it means the information needed to assign a threat category is absent. Given the documented habitat loss across East Kalimantan and the species' apparent restriction to a specialised and shrinking habitat type, it would not be surprising if a future assessment placed it in a threatened category. Hobbyist breeding programmes that maintain self-sustaining captive populations without relying on wild-caught imports represent the most practical contribution the aquarium community can make to the species' long-term security.