Betta Macrostoma

Datasheet

Behaviour

The Brunei Beauty, Betta macrostoma, is not recommended for standard community settings due to its specific requirements. It is best kept alone or with very peaceful species, as larger or more vigorous fishes may intimidate or outcompete it. In some cases, small cyprinids and loaches sharing similar habitats in nature can be compatible. It is advisable to maintain this species in pairs, although temporarily keeping them in a group may be necessary to allow the fish to select their partners. Males tend to engage in incessant fighting when housed together, while females also squabble until a dominance hierarchy forms.

Feeding and Diet

The Brunei Beauty primarily preys on insects, small invertebrates, and zooplankton in its natural habitat, possibly including shrimp. In captivity, they adapt to dried foods but should be regularly provided with small live or frozen foods like Daphnia, Artemia, or bloodworm to maintain optimal color and condition. Larger specimens can occasionally be offered earthworms; however, care should be taken to prevent overfeeding as Betta species are susceptible to obesity.

Reproduction & Dimorphism

Betta macrostoma is a paternal mouthbrooder. Breeding requires a separate tank, ideally with a tight-fitting cover to maintain warm, humid conditions crucial for fry development. The formation of a compatible pair ideally occurs naturally, as randomly selected males and females may not coexist peacefully, potentially leading to aggression or even fatalities. Courtship involves the male displaying intense colors and approaching the female with specific behaviors. The breeding process includes the release of eggs in small batches during embraces, with both adults involved in caring for the fertilized eggs.

Aquarium Setup

The Brunei Beauty thrives in a fully decorated aquarium, often without a substrate for ease of maintenance. Driftwood, roots, branches, clay pots, or piping can be utilized to create shelter and hiding spots. Adding dried leaf litter, such as beech, oak, or Ketapang almond leaves, not only enhances the natural feel but also promotes microbe growth as they decompose, serving as a valuable food source for fry. Dim lighting is preferred, and plant species like Microsorum pteropus or Taxiphyllum barbieri can be included. A gentle air-powered sponge filter is suitable for filtration, and it is essential to keep the tank well-covered and not filled to the top to allow access to the humid air layer above the water surface.

Habitat and Distribution

Endemic to Borneo, Betta macrostoma is specifically found in Brunei Darussalam and the northern area of Sarawak, Malaysia. Its habitat includes still, shady pools at the top of rainforest waterfalls, characterized by fast-flowing, slightly brown water with negligible mineral content and pH levels ranging from 4.4 to 5.7. The species coexists with limited sympatric fish species, primarily Rasbora tubbi, and red-colored shrimp typical in their habitat. Due to its restricted range, it has been designated as Vulnerable (D2) on the IUCN Red List, with conservation efforts in place due to habitat threats like the conversion of Sarawak habitats into oil palm plantations.