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Encyclopedia / Gouramis & Bettas / Brunei beauty
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Variations

1 kinds · tap one for a closer look

Brunei beauty

Betta macrostoma · Spotfin betta, Macrostoma betta, Betta macrostoma

Males are aggressive toward each other; one male per tank.

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10 cmBody length, without tail ✓
20–25 °CTemperature ✓
4–6pH ✓
72 LSmallest tank ✓
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Tank mates
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Not recommended
  • Brunei beauty eats animals up to about 4 cm. Neon tetra only grows to 2.5 cm.
Not recommended
  • Brunei beauty eats animals up to about 4 cm. Cardinal tetra only grows to 3 cm.
Not recommended
  • Brunei beauty eats animals up to about 4 cm. Black neon tetra only grows to 3.2 cm.
With conditions
  • Only a narrow pH range suits both: exactly 6.
With conditions
  • Only a narrow temperature range suits both: 24–25 °C.
  • Only a narrow pH range suits both: exactly 6.
Compatible
Compatible
Compatible
Compatible
Compatible

50 species in our list are a good match.

Facts checked against sources on 16 Oct 2026. ✓ means a source backs it; ? means no reliable source yet. See sources

Care and water

Hardness ✓0–5 dGH
Group size ✓2 or more
Temperament ✓Semi-aggressive
Swims at ?Top
Care level ✓Moderate
Diet Carnivore
Lifespan ?Unknown
Size in shops 5–9 cm
Growth Medium

Behavior

Males are aggressive toward each other; one male per tank. It will eat small fish that fit its large mouth.

Food

Frozen bloodworms, brine shrimp, small fish and shrimp, earthworms.

Tap a food to see what it is.

Male or female

Males grow larger, are more colourful (red), have a broader head and longer fins than females.

Health

Common problems. Tap one to see the signs. This is a guide, not a diagnosis.

Breeding

Mouthbrooder · Hard

Paternal mouthbrooder: the male carries the eggs. Incubation reported as 14-35 days, after which the male releases free-swimming fry. Males often swallow broods if disturbed, so keep the tank quiet; the fry (5 mm+) take microworm and Artemia nauplii at once.

Pairing

A well-fed pair in a roomy tank.

Setup

100 L soft acidic tank with caves, leaf litter and plants.

What starts it

Soft acidic water and meaty foods.

Eggs

30-60 eggs carried by the male.

Raising the fry

Fry are large enough for baby brine shrimp, microworms and grindal worms.

Common mistakes
  • Housing males together
  • Small tankmates getting eaten
Full breeding guide, day-by-day plan and simulator →

Where it lives in the wild

RegionBrunei & northern Sarawak, Borneo
HabitatClear, cool forest streams
Native rangeAbout 100 km across
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The story of the brunei beauty

A large paternal mouthbrooding betta found only in Brunei and the northern tip of Sarawak, Borneo; males are red with a red patch on the gill cover and an eye-spot in the dorsal fin. It is listed as Vulnerable and Brunei has banned its export.

Charles Tate Regan described this betta in 1910. Known as the Brunei beauty, it is one of the most prized and difficult wild bettas.

First described by C. Tate Regan in 1910. Named for 'Macrostoma' means large mouth.

  • It is a mouthbrooder; the male holds the eggs.
  • It lives in clear, fast-flowing forest streams.
  • It is known from only a small area of Brunei and Sarawak.

Sources

16 facts checked with sources