Distribution

The collection locality has been given as ‘jungle of Bulungan’ which seems to refer to Bulungan Regency in East Kalimantan (Kalimantan Timur) province, northern Indonesian Borneo.

Habitat

Thought to be flowing, highland streams as opposed to swamps or other lowland waters.

Maximum Standard Length

Unconfirmed, but likely to be 90 – 100 mm.

An aquarium with base dimensions of 80 ∗ 30 cm would comfortably house a pair though larger quarters would be needed for a group.

Maintenance

Can be maintained in a fully-decorated aquarium although many breeders prefer not to use a substrate for ease of maintenance. Driftwood roots and branches can be used and placed such a way that a few shady spots are formed. If you can’t find driftwood of the desired shape common beech or oak is safe to use if thoroughly dried and stripped of bark. Clay plant pots or lengths of piping can also be included to provide further shelter.

The addition of dried leaf litter (beech or oak is probably best as the popular Ketapang almond leaves tend to leach a lot of tannins which may have an adverse effect on this clearwater species) could further emphasise the natural feel, as well as offering a little extra cover.

Like others in the genus this species seems to do best under fairly dim lighting. You could add Asian plant species that can survive under such conditions, such as Microsorum pteropus, Taxiphyllum barbieri or perhaps some potted Cryptocoryne spp.

A few patches of floating vegetation to diffuse the light would also be useful, and unlike most congeners this species seems to do prefer a little water movement. Also keep the tank well-covered and do not fill it to the top it since Betta spp. require occasional access to a layer of humid air which will form above the water surface, and is an excellent jumper.

Diet

In nature it probably feeds mainly on insects and other invertebrates. It will normally accept dried foods once they are recognised as such but like all fish does best when offered a varied diet. In this case regular meals of live or frozen foods such as Daphnia, Artemia, bloodworm and the occasional small earthworm will ensure the development of the best colours and condition.

Small insects such as crickets or Drosophila fruit flies are also suitable to use though it’s best to fill the stomachs of these by feeding them fish flakes or some kind of vegetable matter before offering them to the fish. Take care not to overfeed as Betta species seem particularly prone to obesity. Some experts have also warned of health problems developing when young fish are fed excessive quantities of Artemia.

Not a recommended choice for the standard community set-up for reasons already touched upon and generally best maintained alone.

Provided the tank is of sufficient size and contains plenty of hiding places/broken lines of sight a group can be maintained together. Although a little squabbling is inevitable, especially between males, it’s relatively peaceful.

Sexual Dimorphism

Males grow larger and possess a greater amount of iridescent scaling on the head and body than females, as well as developing extended fins as they mature. The head profile in males is also noticeably stockier than in females because they are responsible for mouthbrooding eggs and fry.

Reproduction

Paternal mouthbrooder. Has been bred in aquaria.

This hypothetically-undescribed species appears to be a member of the Betta unimaculata complex of closely-related species within the genus, of which members share the following set of characters: body long and slender with depth at dorsal fin origin 18-25 % SL; head large and blunt with width 19-24 % SL; long maxilla and lower lip with distance from tip of lower jaw to posterior end of maxilla 27-54 % HL; caudal-fin rounded in shape, occasionally with elongated median rays; pelvic-fin short and filamentous; dorsal and anal fins relatively pointed.

The genus Betta is the most speciose within the family Osphronemidae with almost 70 recognised members and looks set to grow further with new ones continuing to be described on a regular basis since the turn of the century.

Member species have successfully adapted to inhabit a variety of ecological niches from stagnant ditches to flowing hill streams including some extreme environments such as highly acidic peat swamp forests.

The referral of members to a number of groups containing closely-related species is now generally accepted but largely based on morphological/behavioural characters. Molecular phylogenetic work is thus required and would undoubtedly prove useful in more precisely determining relationships between these fishes.

Like others in the suborder Anabantoidei this species possesses an accessory breathing organ known as the labyrinth. So-called due to its maze-like structure this organ allows the fish to breathe atmospheric air to a certain extent.

Comprising paired suprabranchial organs formed via expansion of the epibranchial (upper) section of the first gill arch and housed in a chamber above the gills, it contains many highly-vascularised, folded flaps of skin which function as a large respiratory surface. Its structure varies in complexity between species, tending to be better-developed in those inhabiting harsher environments.