Blackfin betta
A mouthbrooding Betta, not a bubble-nester, and a fish that lives as a pair rather than in isolation. The trade's image of a Betta as a solitary fish in a small vessel comes entirely from Betta splendens and is wrong for most of the genus, including this one.
Quick profile
- Scientific name
- Betta albimarginata
- Adult size
- 2.5–3.5 cm (1–1.4 in)
- Lifespan
- 3–5 years
- Temperature
- 22–26 °C (72–79 °F)
- pH
- 4.5–6.5
- Hardness
- 0–5 °dGH
- Minimum tank
- 40 L (11 US gal)
- Minimum length
- 45 cm
- Swimming zone
- Bottom
- Social
- Pair
- Diet
- Micropredator
- Overall confidence
- low confidence
What keeping this species involves
Needs soft acidic water, live food and cover, and is otherwise peaceable and undemanding. Nothing about it resembles keeping a Siamese fighting fish.
Small, shallow, shaded forest streams over thick leaf litter.
Identity and names
- Common name
- Blackfin betta
- Scientific name
- Betta albimarginata
- Family
- Osphronemidae
- Order
- Anabantiformes
- Class
- Actinopterygii
- Also sold as
- strawberry betta, Betta albimarginata
Adult size and growth
2.5–3.5 cm (1–1.4 in)
Typical lifespan in an aquarium: 3–5 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.
Water and tank requirements
A pair holds a small area of leaf litter; the requirement is a covered floor with retreats rather than swimming space.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 22–26 °C (72–79 °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 | 40 L (11 US gal) | A floor, not a recommendation. |
| Minimum footprint | 45 cm long | A pair holds a small area of leaf litter; the requirement is a covered floor with retreats rather than swimming space. |
| Water flow | still | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Deep leaf litter, driftwood, dim light and a tightly covered tank with an air gap above the water. |
Behaviour
- Stays low among leaf litter and moves in short deliberate darts.
- A holding male sits still with a visibly distended throat and does not feed.
Telling males from females
Males are orange-red with black-and-white edged unpaired fins and a broader head; females are brown with less fin marking.
Feeding
Small live foods are strongly preferred; dry food is often refused entirely.
- Diet type
- Micropredator
- Staples
- Live and frozen daphnia, cyclops and bloodworm, Live blackworm and grindal
Breeding
- Strategy
- Paternal mouthbrooding
- Difficulty
- straightforward
- Parental care
- mouthbrooding
The male holds eggs and fry in his mouth for roughly two weeks and does not feed while holding.
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 | none | Anything that fits in the mouth is at risk once this species reaches adult size. |
| Adult dwarf shrimp | low | Cover reduces losses but rarely prevents them where the risk is high. |
| Shrimplets | moderate | Determines whether a shrimp colony can grow rather than merely persist. |
| Snails | none | Applies to snails you wanted as well as snails you did not. |
| Long or trailing fins | none | 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.
- Jumps, and needs both a cover and an air gap beneath it; a labyrinth fish gulping chilled air can be harmed by it.
- Sold under the Betta name and then housed like a Siamese fighting fish, which means the wrong water, the wrong food and unnecessary isolation.
- Its wild range is small, and collection pressure on restricted-range Betta species is a live conservation question.
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
- Sebuku river basin, East Kalimantan, Borneo — a very restricted range
- Habitat
- Small, shallow, shaded forest streams over thick leaf litter.
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 albimarginata | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Sebuku river basin, East Kalimantan, Borneo — a very restricted range | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 2.5–3.5 cm | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| lifespan | 3–5 years | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| temperature | 22–26 °C | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| ph | 4.5–6.5 pH | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| general hardness | 0–5 °dGH | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 40 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 45 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 2026-08-12. 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.
Group size and social behaviour
Forms lasting pairs and can be kept as a small group in a mature tank with enough litter. Isolation is not this species' natural state.