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Brunei Beauty
Betta macrostoma
Animalia›Chordata›Actinopterygii›Osphronemidae
📍 Southeast Asia
Betta macrostoma, the Brunei Beauty, is widely considered the most beautiful wild betta species — males display deep orange-red bodies, black-bordered fins, and a striking bicolour pattern. It is a large, powerful mouthbrooder endemic to cool, clear streams in Brunei and Sarawak and is critically endangered in the wild. Keeping it successfully demands expert-level water quality management, cool temperatures, and near-perfect breeding conditions.
Care Guide
Diet
Betta macrostoma are strict carnivores requiring large live or frozen foods such as earthworms, large bloodworms, crickets, and small fish. Feed once daily with portions they can consume in 2-3 minutes. Avoid standard flake foods entirely; this species will not thrive on pellets alone and requires protein-rich whole prey items.
Behavior
This is a territorial and aggressive species, especially males, which will fight viciously if confined together. They are powerful swimmers that patrol mid-water levels and display elaborate courtship behaviors during breeding season. Males are highly aggressive toward rivals but form stable pair bonds with females when breeding conditions are met.
Breeding
Betta macrostoma are paternal mouthbrooders requiring expert-level care to breed successfully. Breeding is rare in captivity and demands pristine cool water (20–22°C), excellent water quality, and a bonded pair in a species-only tank. Fry are large and can be fed small live foods immediately after release from the male's mouth.
Tank Mates
Peaceful algae eater; may be tolerated but monitor closely as macrostoma may view small fish as prey
Large shrimp less likely to be eaten; still requires careful observation in a species-only setup
Hardy plant provides shelter and does not require high light; ideal for cool, low-tech setups
Shade-loving plant that thrives in cool water and provides cover without competing for space
Slow-growing plant suited to cool, acidic water; creates natural habitat structure
Common Diseases
Fin Rot
Frayed, discolored, or deteriorating fin edges; lethargy and reduced appetite
Perform 25% water changes every 2-3 days, maintain pristine water quality, and consider antibacterial medication (e.g., tetracycline) if condition worsens
Ich (Ichthyophthirius multifiliis)
White spots on body and fins, excessive scratching against surfaces, rapid breathing
Raise temperature gradually to 24–25°C (if tolerated), perform daily water changes, and treat with ich medication; avoid heat shock as this species prefers cool water
Bacterial Infection
Cloudy eyes, open sores, swollen belly, torn fins, loss of appetite
Improve water quality immediately, perform 50% water change, and administer broad-spectrum antibiotics if infection is severe
Parasitic Infection
Excessive scratching, weight loss, visible worms or parasites, clamped fins
Quarantine affected fish, treat with antiparasitic medication, and maintain excellent water quality to prevent secondary infections
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Quick Facts
- diet
- Carnivore – large live/frozen foods: earthworms, large bloodworms, crickets
- breeding
- Paternal mouthbrooder; pair bonding required
- lifespan
- 5–8 years
- max size
- 11 cm (4.3 in)
- tank size
- 20 gallons minimum; species-only tank strongly recommended
- temperament
- Territorial; males fight; keep as single pair only
Water it likes
- ph
- 4.5–6.5
- ammonia
- 0 ppm
- nitrate
- <5 ppm
- hardness
- 1–5 dGH
- temperature
- 68–77°F (20–25°C)