Betta macrostoma Breeding Guide
Breeding the prized Brunei Beauty Betta macrostoma: a cool soft-water paternal mouthbrooder with a long, variable oral incubation period.
Overview
Betta macrostoma, the Brunei Beauty, is a prized paternal mouthbrooder endemic to Borneo, where it inhabits still, shady pools at the top of rainforest waterfalls with negligible mineral content. The male incubates the eggs and fry orally. It is an advanced species that demands cool, very soft, acidic water.
Sexing
Males tend to grow larger, are more colourful, have a broader head shape and possess more extended fins than females. The broad cranial profile in mature males accommodates the developing brood.
Breeding Setup
- Temperature: 20-25 C (notably cool for a tropical betta)
- pH: 4.0-6.0
- Hardness: 0-90 ppm (very soft)
- Still water with shade and cover, minimal mineral content
Recreating the cool, mineral-poor, shaded pool conditions of its native waterfalls is central to success with this species.
Spawning Behavior & Trigger
Courtship involves an intensely-coloured male approaching the female with mouth gaping and fins erect. Fertilisation occurs in an embrace typical of osphronemids in which the male wraps his body around the female, after which he collects and incubates the eggs orally.
Egg & Fry Care
The incubation period is highly variable, with reports ranging from 14 to 35 days, after which the male begins to release fully-formed, free-swimming fry. Fry are big enough (5 mm and over) to accept motile foods such as microworm and Artemia nauplii immediately. Offer small amounts of different foods several times per day, with small daily water changes of around 5-10% of tank volume.
Common Challenges
The very long and variable incubation tests a holding male's reserves, and disturbance can cause him to release the brood early. Maintaining stable cool, soft, acidic water and an undisturbed environment throughout the holding period is essential.