Spotfin betta
A large mouthbrooding Betta with an orange-and-black patterned body, restricted to a handful of streams in Brunei and among the most sought-after fish in the hobby. It is a cool-water stream fish rather than a warm still-water one, which is the requirement most often missed.
Quick profile
- Scientific name
- Betta macrostoma
- Adult size
- 8–11 cm (3.1–4.3 in)
- Lifespan
- 5–8 years
- Temperature
- 21–25 °C (70–77 °F)
- pH
- 4.5–6.5
- Hardness
- 0–5 °dGH
- Minimum tank
- 100 L (26 US gal)
- Minimum length
- 80 cm
- Swimming zone
- All levels
- Social
- Pair
- Diet
- Carnivore
- Overall confidence
- moderate confidence
What keeping this species involves
Cool soft acidic water, live food, a sealed lid and a quiet tank. It is among the most demanding Betta species and is priced accordingly.
Cool, shaded, fast-flowing forest streams over sand and leaf litter, in soft acidic water.
Identity and names
- Common name
- Spotfin betta
- Scientific name
- Betta macrostoma
- Family
- Osphronemidae
- Order
- Anabantiformes
- Class
- Actinopterygii
- Also sold as
- Betta macrostoma, Brunei beauty, peacock mouthbrooder, macrostoma
Adult size and growth
8–11 cm (3.1–4.3 in)
Typical lifespan in an aquarium: 5–8 years. Almost every animal sold in a shop is a juvenile, so the tank has to suit the size in the first line rather than the size in the bag.
Shape, which is what the compatibility engine reads instead of length alone: deep-bodied with a small terminal mouth. Assigned from what is typical of Osphronemidae, not examined for this species.
Water and tank requirements
A pair holding a stream territory, in a tank with enough length for the female to retreat during and after spawning.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
Why these ranges: Shaded Bornean hill streams are cool, soft and strongly acidic. This species is notably intolerant of warm water and is reported to develop disease problems above the mid-twenties, which makes the ceiling a real limit rather than a preference.
Where these figures come from
Habitat class
Blackwater
Tannin-stained water draining podzolic forest sand, carrying almost no dissolved mineral and a heavy load of humic and fulvic acid.
The defining property is the absence of mineral, not the colour. Water this soft has almost no buffering, so pH moves fast and a keeper's job is stability rather than chasing the wild figure.
- Conductivity
- 8–40 µS/cm
- Flow
- low
- Dissolved oxygen
- moderate
- Seasonality
- strong
These are figures for the KIND of water body, not measurements of this species. They are AquariumHQ’s summary of the general limnology and are given wide because the water is.
- TemperatureReasoned on this record
- This record states its own reason for this band. See the water section.
- pHReasoned on this record
- This record states its own reason for this band. See the water section.
- General hardnessReasoned on this record
- This record states its own reason for this band. See the water section.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 21–25 °C (70–77 °F) | Stability matters more than hitting an exact figure. |
| pH | 4.5–6.5 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 0–5 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 100 L (26 US gal) | A floor, not a recommendation. |
| Minimum footprint | 80 cm long × 40 cm deep | A pair holding a stream territory, in a tank with enough length for the female to retreat during and after spawning. |
| Water flow | moderate | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Leaf litter, wood, caves and dim light, with a tightly sealed lid. Humid air above the water is part of the requirement. |
Behaviour
- Males display by flaring the gill covers and dorsal fin fully, holding the posture for extended periods.
- A brooding male sits low in the tank with a visibly distended throat and does not feed for the duration.
Telling males from females
Males are orange and black with a large patterned dorsal fin and become intensely coloured when displaying. Females are brown with dark horizontal bars.
Feeding
A predator of insects and small invertebrates that frequently refuses dry food. Live and frozen feeding is close to a requirement.
- Diet type
- Carnivore
- Staples
- Live blackworm, Frozen bloodworm, Live daphnia, Frozen mysis
Breeding
- Strategy
- Paternal mouthbrooding for roughly a month after an embrace at the substrate
- Difficulty
- challenging
- Parental care
- mouthbrooding
The male holds the eggs and fry without feeding. Disturbing him causes him to swallow or release the brood, which is why the tank has to be quiet.
Tankmates and compatibility
Assessments are derived from stored traits by the compatibility engine, with the reasoning shown. A verdict is a statement about probability, not a guarantee — individual temperament can override it.
| Towards | Risk | What it means |
|---|---|---|
| Small fish | high | Anything that fits in the mouth is at risk once this species reaches adult size. |
| Adult dwarf shrimp | near-certain | Cover reduces losses but rarely prevents them where the risk is high. |
| Shrimplets | near-certain | Determines whether a shrimp colony can grow rather than merely persist. |
| Snails | low | Applies to snails you wanted as well as snails you did not. |
| Long or trailing fins | occasional | Fin damage is an entry point for secondary infection. |
| Plants | none | Tough species such as Anubias and Java fern survive most grazers. |
Any pair in the catalogue can be assessed with the compatibility checker.
Welfare considerations
Points where the way this species is commonly sold or kept differs from what it actually needs.
- Restricted to a very small wild range, historically subject to collection pressure and now largely supplied by captive breeding. Buying captive-bred stock is the meaningful choice here.
- Jumps hard, particularly at night and after a water change. Every gap in the lid needs closing rather than most of them.
Problems to watch for
Most problems in a tank containing this species are general rather than species-specific. Start with the troubleshooting index and work from the observation rather than from a guess at the cause.
What AquariumHQ does not yet hold
Species-level disease susceptibility is modelled in the graph and is not yet populated. Health pages will not be published until each condition has veterinary sourcing, because health content written without evidence is the most harmful thing this product could publish. The gap is recorded in the coverage report.
Where it comes from
- Native range
- Borneo — a small number of forest streams in Brunei and adjacent Sarawak
- Habitat
- Cool, shaded, fast-flowing forest streams over sand and leaf litter, in soft acidic water.
What the checklists say
2 distribution statements retrieved from GBIF checklists. Establishment means is reproduced from the source where it states one, and left unstated where it does not — a record of presence is not a record of origin.
| Status | Places | What this means |
|---|---|---|
| Recorded as present, establishment means not stated | 2 | The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in. |
No checklist AquariumHQ holds positively calls this species native anywhere, so the native range above rests on AquariumHQ’s own reading of the literature rather than on a cited checklist.
Evidence
Every stored value with the kind of support behind it and where to check it. Evidence type and confidence are separate axes: an editorial position held confidently and a measurement held tentatively are different things.
| Claim | Value | Evidence type | Confidence | Source |
|---|---|---|---|---|
| scientific name | Betta macrostoma | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Borneo — a small number of forest streams in Brunei and adjacent Sarawak | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 8–11 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 5–8 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 21–25 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 4.5–6.5 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 0–5 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 100 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 80 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
Last reviewed 2026-08-10. Values labelled as an aquarium-literature consensus are AquariumHQ editorial positions rather than measurements — see how evidence is handled.
Why we say this
What each figure on this page rests on, and how far that is from being independently established.
Every figure on this page has a provenance. Open any claim to see what AquariumHQ holds for it, which sources say what, and what a claim of that kind actually needs. Different claims need different evidence: an accepted scientific name is settled by one authority, while a legal restriction needs a current primary instrument. A single source is often the right answer rather than a thin one.
scientific nameAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: accepted scientific name and classification — 1 authoritative source in an appropriate context. Checked against gbif on 2026-08-29. One authoritative backbone is what this class requires.
What would improve this: Go and read a source. This is reachable and has not been reached.
native rangeAquariumHQ's own position, externally checkableLimited evidence — treat with caution.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: where the species occurs — 1 authoritative source in an appropriate context. 2 distribution statements held, and not one of them states an establishment means. Presence without native-or-introduced is not a native-range claim, so this stays below requirement rather than being read as one.
What would improve this: Go and read a source. This is reachable and has not been reached.
adult sizeAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
lifespanAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
temperatureAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
phAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
general hardnessAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
minimum tank volumeAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
minimum tank lengthAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
Guides relevant to this species
Chosen from this record's own traits rather than listed on every page.
- Predator and prey sizeIt takes fish that fit in its mouth, and its mouth grows with it.
- Territorial behaviourIt defends ground, and the shape of what it defends decides the tank more than the volume does.
- Wild conditions and aquarium recommendationsThe water band on this page is an AquariumHQ position with a stated reason, not a measurement of a river.
- How to read a compatibility verdictThis animal's fins are a target, and most compatibility verdicts about that are derived rather than observed.
Group size and social behaviour
Kept as a pair. Males are territorial towards each other and the spawning process is demanding on the female, so she needs somewhere to go.