Devil loach
A tiny loach in a family of its own, marked in gold and black and rarely still. It is one of the few genuinely nano-sized loaches, and its family placement — Barbuccidae, separated from the Balitoridae — is recent enough that most sources still file it elsewhere.
Quick profile
- Scientific name
- Barbucca diabolica
- Adult size
- 2.5–3.5 cm (1–1.4 in)
- Lifespan
- 3–5 years
- Temperature
- 22–27 °C (72–81 °F)
- pH
- 5.5–7.2
- Hardness
- 1–10 °dGH
- Minimum tank
- 45 L (12 US gal)
- Minimum length
- 60 cm
- Swimming zone
- Bottom
- Social
- Loose group — at least 6
- Diet
- Micropredator
- Overall confidence
- low confidence
What keeping this species involves
Undemanding about water and demanding about substrate, cover and group size. It is also small enough to be eaten by a great many things.
Small, shaded, moderately flowing forest streams over sand and leaf litter, in soft acidic water.
Identity and names
- Common name
- Devil loach
- Scientific name
- Barbucca diabolica
- Family
- Barbuccidae
- Order
- Cypriniformes
- Class
- Actinopterygii
- Also sold as
- Barbucca diabolica, diabolical loach, hillstream barbucca
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.
Shape, which is what the compatibility engine reads instead of length alone: elongate with a small terminal mouth. Assigned from what is typical of Barbuccidae, not examined for this species.
Water and tank requirements
A small benthic fish that works a floor area and needs continuous sand with cover. Footprint rather than volume.
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 Sundaland forest stream: soft, slightly acidic and moderately flowing, without the extreme chemistry of the peat swamps nearby. The distinction matters — this is a stream fish rather than a swamp one, and it wants more oxygen than its neighbours.
Where these figures come from
Habitat class
Soft forest stream
Shaded, mineral-poor running water under forest canopy, with leaf litter and moderate tannin loading but without true blackwater chemistry.
The commonest habitat class in the aquarium trade and the one the conventional community-tank setting actually fits. Soft and slightly acidic, without the extremes that make blackwater difficult.
- Conductivity
- 20–120 µS/cm
- Flow
- low
- Dissolved oxygen
- moderate
- Seasonality
- moderate
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 | 22–27 °C (72–81 °F) | Stability matters more than hitting an exact figure. |
| pH | 5.5–7.2 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 1–10 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 45 L (12 US gal) | A floor, not a recommendation. |
| Minimum footprint | 60 cm long | A small benthic fish that works a floor area and needs continuous sand with cover. Footprint rather than volume. |
| Water flow | moderate | Match the outflow to this rather than to the filter's rating. |
| Lid required | Recommended | Reduces evaporation and prevents accidents. |
| Structure | Fine sand, leaf litter, smooth stone and moderate flow. |
Behaviour
- Moves in short darts across sand and rests propped on its pectoral fins.
- Most active at dusk and after lights out.
Telling males from females
Not reliably distinguishable outside breeding condition.
Feeding
- Diet type
- Micropredator
- Staples
- Frozen cyclops and daphnia, Live baby brine shrimp, Sinking micro pellets
Breeding
- Strategy
- Not established in aquaria
- Difficulty
- rarely achieved
- Parental care
- none
AquariumHQ holds no account of this species being bred deliberately.
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 | none | 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.
- Wild-caught and uncommon in the trade. It arrives thin and needs feeding up on small live and frozen food.
- Filed under Balitoridae by many sources; the accepted family is Barbuccidae, which matters when looking for care information.
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 and the Malay Peninsula — small forest streams in Kalimantan and Sarawak
- Habitat
- Small, shaded, moderately flowing forest streams over sand and leaf litter, in soft acidic water.
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 | Barbucca diabolica | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Borneo and the Malay Peninsula — small forest streams in Kalimantan and Sarawak | 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 | 22–27 °C | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| ph | 5.5–7.2 pH | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| general hardness | 1–10 °dGH | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 45 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 60 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum group size | ≥ 6 | AquariumHQ editorial position | low 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 2026-08-30. 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. No checklist distribution statement is held for this species. The range on the page is editorial until one is.
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.
minimum group sizeAquariumHQ'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: group size — 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: 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.
- Schooling and shoalingThis species is recorded as loose group, and the number it is kept in decides how it behaves.
- Wild conditions and aquarium recommendationsThe water band on this page is an AquariumHQ position with a stated reason, not a measurement of a river.
Group size and social behaviour
Lives in loose aggregations and is far bolder in a group. Singletons hide permanently.