Barred bichir
A mid-sized bichir marked with dark vertical bars on a grey-green body, reaching around thirty-five centimetres and generally reckoned the best-tempered of the commonly available species. It is a realistic large-tank fish in a way several of its relatives are not.
Quick profile
- Scientific name
- Polypterus delhezi
- Adult size
- 30–40 cm (11.8–15.7 in)
- Lifespan
- 12–20 years
- Temperature
- 24–29 °C (75–84 °F)
- pH
- 6–7.8
- Hardness
- 3–18 °dGH
- Minimum tank
- 350 L (92 US gal)
- Minimum length
- 150 cm
- Swimming zone
- Bottom
- Social
- Loose group — at least 2
- Diet
- Carnivore
- Overall confidence
- moderate confidence
What keeping this species involves
Hardy, long-lived and comparatively mild, needing a large tank, sand, a sealed lid and tankmates too big to swallow.
Slow river margins and backwaters with soft bottoms and submerged wood, in warm soft water.
Identity and names
- Common name
- Barred bichir
- Scientific name
- Polypterus delhezi
- Family
- Polypteridae
- Order
- Polypteriformes
- Class
- Actinopterygii
- Also sold as
- Polypterus delhezi, delhezi, banded bichir, armoured bichir
Adult size and growth
30–40 cm (11.8–15.7 in)
Typical lifespan in an aquarium: 12–20 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 large — a piscivore's mouth. Assigned from what is typical of Polypteridae, not examined for this species.
Water and tank requirements
A thirty-five-centimetre bottom fish that needs floor area and surface access. Height contributes nothing.
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: Congo basin river water, warm and soft to moderate. The species is tolerant within the band and cares more about substrate and cover.
Where these figures come from
Habitat class
Lowland floodplain
Seasonally inundated flat country — várzea, chaco, swamp margin — where the water body changes size, depth and chemistry through the year.
The habitat's defining feature is change, so a single band describes it badly. Species from here are generally tolerant of a wide range and intolerant of nothing much — which makes them easy to keep and easy to keep wrongly.
- Conductivity
- 40–300 µS/cm
- Flow
- still
- Dissolved oxygen
- low
- 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 | 24–29 °C (75–84 °F) | Stability matters more than hitting an exact figure. |
| pH | 6–7.8 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 3–18 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 350 L (92 US gal) | A floor, not a recommendation. |
| Minimum footprint | 150 cm long × 50 cm deep | A thirty-five-centimetre bottom fish that needs floor area and surface access. Height contributes nothing. |
| Water flow | low | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Soft sand, caves and wood, with a sealed lid and unobstructed access to the surface. |
Behaviour
- Rests under cover through the day and works the substrate at night using scent.
- Retains external gills as a juvenile, which are gradually lost, so a very young bichir looks like an amphibian larva.
Telling males from females
Males have a broader, thicker anal fin. Not readable in juveniles.
Feeding
Hunts by scent along the substrate. Sinking food placed near the fish is what reliably reaches it.
- Diet type
- Carnivore
- Staples
- Earthworm, Prawn, Frozen mysis, Sinking carnivore pellets, Mussel
- Avoid
- Live feeder fish, Mammalian meat
Breeding
- Strategy
- Eggs deposited among vegetation, with no parental care
- Difficulty
- rarely achieved
- Parental care
- none
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 | near-certain | 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 | moderate | 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.
- Sold as a small oddity at eight centimetres and reaching forty. Its temperament makes it one of the more reasonable large predators to keep, and the tank is still a large one.
- Bichirs are notorious escapers and will use any gap including the space around a filter pipe. The lid has to be sealed rather than merely present.
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
- The upper and middle Congo basin
- Habitat
- Slow river margins and backwaters with soft bottoms and submerged wood, in warm soft water.
What the checklists say
4 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 |
|---|---|---|
| Introduced | 1 | A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal. |
| Recorded as present, establishment means not stated | 3 | 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 | Polypterus delhezi | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | The upper and middle Congo basin | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 30–40 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 12–20 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 24–29 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 6–7.8 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 3–18 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 350 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 150 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum group size | ≥ 2 | 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 checkableBased on a verified authoritative source.
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. 4 distribution statements held from GBIF checklists — introduced in 1 country. Establishment means is reproduced from the source, never inferred from occurrence.
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.
- Predator and prey sizeIt takes fish that fit in its mouth, and its mouth grows with it.
- Wild conditions and aquarium recommendationsThe water band on this page is an AquariumHQ position with a stated reason, not a measurement of a river.
- Rehoming an animal you can no longer keepThis animal reaches 40 cm. Most of the difficult rehoming cases are fish sold small that were always going to become impossible.
Group size and social behaviour
Sociable for a large predator and generally kept in small groups. Competition is over food rather than territory.