Taxonomy & naming
Betta edithae was formally described by the German aquarist and ichthyologist Jörg Vierke in 1984. The type locality is the Barito River delta at Bandjarmasin (modern spelling Banjarmasin), South Kalimantan, Borneo, Indonesia; the holotype is SMF 18712 and a paratype is SMF 18713 in the Senckenberg Museum, Frankfurt. The valid name as recorded in Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Van der Laan) is Betta edithae Vierke, 1984, placed in the family Osphronemidae.
Within Betta, the species is assigned to the edithae group, a clade separated from the larger complex of Betta species by a distinctive combination of opaque to translucent branchiostegal membranes and the pattern on the posterior opercle — characters visible in hand without specialised equipment. The group is one of several mouthbrooding lineages within a genus that spans both bubblenesting and mouthbrooding reproductive modes. No subspecies are recognised.
Morphology
Betta edithae is a moderately sized wild betta, reaching around 2–2.5 in standard length according to Seriously Fish, with FishBase recording a maximum total length of 3 in. The body is the typical elongate-oval form of the genus, with a somewhat broader, flatter head than seen in bubblenesting species — a feature associated with the mouthbrooding habit, as the male must accommodate a clutch of eggs and early fry in the buccal cavity.
Coloration is subtle rather than showy. Males develop a more intensely iridescent head and gill-cover scaling than females, with a broader head profile and extended unpaired fins; a brilliant iridescent band runs along the anal and caudal fins of displaying males. Females are recognisably smaller, with a more rounded body and the absence of extended fin rays; gravid females can be identified by visible ovaries when spotlit from the side. The species lacks the extreme finnage of domesticated Betta splendens; its appeal is the quiet shimmer of wild-type iridescence rather than artificially selected colour.
Habitat
Betta edithae occurs across the Greater Sunda Islands — Kalimantan (Indonesian Borneo), Sumatra, and the adjacent islands of Bangka, Belitung, and Bintan — wherever suitable blackwater lowland habitat exists. In Kalimantan the type locality sits in the Barito River delta, one of the great peat-swamp systems of Southeast Asia. The species inhabits flowing blackwater streams, sluggish canals bordered by oil palm plantations, and the stiller marginal zones of such watercourses, where submerged root masses and accumulations of leaf litter provide shelter and structure.
Water chemistry is the defining ecological signature: soft, acidic, and strongly tannin-stained. Seriously Fish records a pH range of 5.0–7.0 and conductivity of 18–90 ppm, with temperatures of 68–81 °F. FishBase notes it as a facultative air-breather, which is characteristic of all labyrinth fishes (family Osphronemidae) — the suprabranchial organ supplements gill respiration and allows survival in oxygen-depleted peat-swamp water where few other vertebrates persist. Stagnant or near-stagnant, deeply shaded water with surface access is therefore the ecological baseline rather than an exception.
Feeding
In the wild Betta edithae is an insectivore and opportunistic invertebrate predator, taking insects, small aquatic invertebrates, and likely zooplankton from the water column and surface film of its peat-swamp habitat. The natural diet is protein-rich and taxonomically diverse, as befits a predator in a structurally complex blackwater environment.
In the aquarium the species readily accepts live foods — small live insects and invertebrates are taken eagerly — and transitions well to frozen alternatives: Daphnia, Artemia (brine shrimp), and bloodworm are all reported as accepted. Dried foods meet more resistance; flake foods are not readily taken, though small micro-pellets can be introduced successfully with patience. Feeding live or frozen foods remains the best way to maintain condition and bring fish into spawning readiness.
Mating
Betta edithae is a paternal mouthbrooder. The mating embrace follows the pattern typical of the family Osphronemidae: the male wraps his body around the female in a characteristic embrace during which eggs are fertilised. After the embrace the female expels the eggs and the male collects them directly into his mouth — in some observations the female spits the eggs toward the male, who gathers them before they can sink. The spawning ritual is secretive and largely hidden within the clutter of vegetation and roots; in an aquarium the first outward sign is often simply the sight of the male with a distended throat.
Females have been reported to initiate spawning, which is unusual and suggests that in this species the female plays an active role in stimulating the male to attend. Embrace bouts can extend over four to five hours as successive clutches of eggs are produced and collected. The complete clutch amounts to roughly 80–100 fry.
Breeding
Once the male has gathered all fertilised eggs, he retires and eats nothing for the entire incubation period, which lasts 9–16 days according to Seriously Fish and 14–20 days according to IBC breeders, with variation depending on temperature and individual. During this period the eggs develop into free-swimming fry within the buccal cavity, sustained by yolk reserves. The male releases the majority of the fry — typically in the evening — at around 0.5 in total length, at which point they are already capable of directed swimming and independent feeding.
Fry accept microworms and freshly hatched brine shrimp nauplii from the outset. In captivity, brooding males are best housed without disturbance in a species tank or a well-covered container where they will not be harassed into spitting the clutch prematurely. Females may attempt to re-spawn before the male has released the current brood; separating the sexes after spawning and reuniting them later is the standard management approach. Lifespan with good care is reported at three years or more.
In the aquarium
Betta edithae is kept successfully by dedicated wild-betta hobbyists and is occasionally encountered in the ornamental trade. A pair or small group can be accommodated in a 10-gallon aquarium; groups of multiple pairs benefit from a 20-gallon or larger tank with dense planting and broken sightlines to allow subordinate fish to escape visual harassment. Cover is important — floating plants, surface leaf litter, and tangles of roots or driftwood replicate the structural complexity of the natural habitat and give brooding males a retreat.
Water chemistry should track the blackwater origins of the species: soft, acidic water in the pH 5.0–6.5 range is ideal, though the species shows some tolerance and has been kept successfully at pH up to 7.5. Temperatures of 75–82 °F suit the species in captivity. Gentle filtration — a sponge filter is standard — is preferred because the natural habitat is still to sluggish; strong circulation inhibits natural behaviour. As a labyrinth fish it must have unobstructed access to the surface for air-breathing; a tight-fitting lid is important to maintain warm, humid air above the water surface, as labyrinth organs are damaged by cold draughts. Tankmates, if any, should be small and non-aggressive species unable to compete for the mouthbrooding male's attention.
Conservation
Betta edithae is assessed as Least Concern (LC) on the IUCN Red List, most recently evaluated on 18 January 2019. The relatively broad distribution across the Greater Sunda Islands — Kalimantan, Sumatra, Bangka, Belitung, and Bintan — provides a buffer that justifies the LC designation despite pervasive regional habitat pressures. Sunda-region peat-swamp habitats have nonetheless experienced severe degradation through drainage, fire, agricultural conversion (primarily to oil palm), and logging over recent decades, and many of the lowland blackwater systems this species depends upon have been substantially altered.
FishBase notes the species as occurring occasionally in the ornamental trade. A 2019 conservation workshop reviewing the status of Sunda-region fishes (published on ResearchGate) confirmed the LC assessment. The species is unlikely to be immune to the broader trajectory of peat-swamp loss in Southeast Asia, and its continued presence in the aquarium hobby supports ex-situ knowledge of its biology.