White Seam Betta

The white seam betta (Betta albimarginata) is a small, exquisitely marked mouthbrooding betta species endemic to the Sebuku River drainage in East Kalimantan, Indonesian Borneo. It inhabits very shallow forest streams (depth ~5–10 cm) with moderate flow, where it lives among marginal plant roots and leaf litter. Described scientifically by Kottelat and Ng in 1994, it belongs to the B. albimarginata group, characterised by 9–12 anal-fin spines—far more than any other Betta species. Its common name derives from the broad white distal band on the fins, contrasting with a dark submarginal band and plain red inner portion.

Males reach 25–30 mm (1–1.2 in) in standard length and are more colourful with a broader head shape than females. A pair or small group can be housed in an aquarium with base dimensions of 45 × 30 cm (approximately 41 L / 11 gal). Despite its small size, this species is not recommended for the standard community aquarium due to its specialised water requirements and retiring disposition. It is best maintained alone or with very small, peaceful species that share its need for soft, acidic water. The aquarium should be dimly lit with driftwood, dried leaf litter, and floating vegetation, with gentle filtration via an air-powered sponge filter.

As a paternal mouthbrooder, the male incubates eggs in his mouth for 10–21 days before releasing fully-formed, free-swimming fry. Brood sizes are small, with even 10 eggs considered a good number. In the aquarium, the diet should consist primarily of small live and frozen foods such as Daphnia, Artemia, and bloodworm, supplemented by dried foods once recognised as edible. Water conditions must be acidic with negligible hardness: temperature 23–28°C, pH 4.0–6.5, and hardness 18–90 ppm. A reverse osmosis unit is typically necessary to achieve these parameters. The labyrinth organ allows this species to breathe atmospheric air, and access to a warm, humid air layer above the water surface is essential.