Taxonomy & naming
Betta stiktos was formally described by Tan Heok Hui and Ng Heok Hee in 2005, in a paper published through the Raffles Bulletin of Zoology (supplement). The holotype, catalogued as CAS 204326 and measuring 2 in standard length, was collected from a small swampy stream on the road from Stung Treng to Ban Lung, approximately three-quarters of the way across the bridge over the Tonle Srepok River, at approximately 13°30′N, 106°30′E, in Stung Treng province, Cambodia — a site within the Mekong drainage basin. Eschmeyer's Catalog of Fishes (CAS) records the valid name as Betta stiktos Tan & Ng, 2005.
The species belongs to the splendens group, the clade of bubble-nesting bettas that includes Betta splendens and several other Mainland Southeast Asian relatives. Within this group, B. stiktos is distinguished by a combination of morphological characters: the presence of a dorsal ocellus (eye-spot) in males, an iridescent operculum, and a broadly lanceolate caudal fin. The specific epithet stiktos derives from the Greek word for 'spotted' or 'dotted', an allusion to the spotted or punctate markings visible on preserved specimens — dark markings on a lighter brown ground colour that gave Tan and Ng the basis for the name.
Morphology
Betta stiktos is a small fish, reaching approximately 1 in standard length, putting it at the smaller end of the splendens group. The body form is typical of the group: moderately elongate and laterally compressed, with the dorsal and anal fins running much of the body length and the caudal fin broadly lanceolate in males — elongated to a point rather than rounded or forked.
Males in life show a yellowish-brown to olive-brown body with iridescent scale patches on the operculum (gill cover) and flanks that reflect blue or green in raking light. A distinctive ocellus — a dark, eye-like spot ringed with iridescent scales — is present in the dorsal fin, a character useful in separating B. stiktos from some congeners. Females are less iridescent and lack the prominent dorsal ocellus, following the typical sexual dimorphism of the group. In preserved material, both sexes are dark brown dorsally and pale brown ventrally, with distinct dark markings on the flanks and unpaired fins.
Habitat
The type locality of Betta stiktos is a small swampy stream in the lowlands of Stung Treng province, Cambodia, within the Mekong basin. The habitat is characterised as blackwater — tea-coloured, tannin-stained water derived from decomposing leaf litter and peat — with a soft, acidic chemistry. Recorded water parameters at the type site include a pH around 5.5 and temperature approximately 75 °F, conditions typical of Southeast Asian peat-swamp and slow forest-stream habitats.
As a labyrinth fish, B. stiktos possesses a suprabranchial organ that allows it to breathe atmospheric air directly from the surface — a critical adaptation for still, shallow, oxygen-depleted blackwater environments where dissolved oxygen can be very low. The species likely occupies marginal swamp areas, sluggish forest streams, and pools with abundant surface vegetation and leaf litter, as is typical for splendens-group bettas in similar habitats across Mainland Southeast Asia. Its exact range within Cambodia remains poorly characterised.
Feeding
Like other members of the splendens group, Betta stiktos is a carnivorous predator of small invertebrates in the wild. The natural diet consists primarily of aquatic insect larvae, small crustaceans, zooplankton, and any invertebrates small enough to be taken at or near the water surface and in the mid-water column. Bettas in blackwater habitats also consume terrestrial insects that fall onto the water surface.
In the aquarium, the species accepts live and frozen invertebrate foods readily — Artemia, Daphnia, bloodworm, and similar items are all appropriate — and most individuals can be weaned onto small, high-quality prepared foods over time. Feeding frequency should be moderate and portions small, as splendens-group bettas can be prone to overeating if offered large quantities.
Mating
Betta stiktos is a bubble-nester. The male constructs a raft of mucus-bound air bubbles at the water surface, typically anchored beneath a floating leaf, a broad-leaved plant, or another surface object that provides overhead cover. The nest-building is initiated by the male and may take hours to days before he courts a female.
Courtship follows the typical splendens-group pattern: the male displays to the female with fins fully flared, body arched, and iridescent scales at maximum reflectance. A receptive female approaches the nest site, and the pair engage in a spawning embrace beneath or beside the nest — the male wraps his body around the female in the characteristic anabantoid nuptial clasp, and the female releases eggs while temporarily stunned. The male collects falling eggs in his mouth and spits them into the bubble-nest, repeating the cycle until the female is spent.
Breeding
Following spawning, the female is driven away from the nest site — or removed by the aquarist — and the male assumes sole parental care. He tends the bubble-nest assiduously, retrieving any eggs or newly hatched larvae that fall and replacing them in the nest, and adding new bubbles to maintain the raft's integrity. The eggs are guarded aggressively against any perceived threat.
At temperatures around 75–79 °F the eggs hatch in approximately 24–48 hours. The larvae are initially tiny, hanging vertically in the water column below the nest, and the male continues to retrieve and replace them until they are free-swimming — typically within two to three days of hatching. At that point, the male's parental role diminishes and the fry begin to disperse. First foods for the fry should be very fine: infusoria, paramecia, or commercial micro-fry foods, graduating to newly hatched brine shrimp nauplii as the fish grow. The male should be removed once the fry are reliably free-swimming to prevent predation.
In the aquarium
Betta stiktos is an uncommon species in the hobby, occasionally available through specialist wild-betta breeders. Its care requirements are broadly similar to other small, blackwater splendens-group bettas: soft, acidic water is strongly preferred, with pH around 5.5–6.5 and temperature in the low-to-mid 20s Celsius, mirroring the conditions at the type locality. Tannin-rich water — achievable with Indian almond leaves, peat filtration, or commercially prepared blackwater extracts — benefits the species both physiologically and behaviourally.
As a labyrinth fish it must have unobstructed access to the water surface to breathe atmospheric air; a close-fitting lid also maintains the warm, humid air layer above the water that protects the delicate labyrinth organ. Filtration should be gentle — the species comes from still or nearly still swamp water and is not adapted to current. A well-planted species tank of at least 5.5–10 US gal, with floating plants providing surface cover for nest-building, is the recommended setup. Males are aggressive toward one another and toward females outside of spawning condition; the species is best kept as a single male with one or two females, or as a single specimen. Tankmates should be chosen with care: very small, non-aggressive species that share the same water-chemistry preferences are appropriate.
Conservation
Betta stiktos is assessed as Data Deficient (DD) on the IUCN Red List, with the most recent assessment dated 2012. A Data Deficient listing does not imply that the species is safe — it reflects the absence of sufficient information on its distribution, population size, and ecology to make a reliable assessment of extinction risk. The species is known from a single type locality in Stung Treng province, Cambodia, and its full range within the Mekong system remains undocumented.
The blackwater swamp and forest-stream habitats of lowland Cambodia face ongoing pressure from agricultural conversion, deforestation, and wetland drainage. Stung Treng province, though relatively remote, is not immune to these trends. Without systematic surveys to establish the species' true range and abundance, its vulnerability to habitat loss cannot be quantified. Hobbyist records and observations from field collectors represent the primary contemporary information about the species' occurrence, underlining the value of the specialist wild-betta community in maintaining knowledge of and captive populations of obscure Southeast Asian bettas.