Elephantnose fish
Navigates and hunts using a weak electric field generated by an organ in the tail, and has a brain-to-body mass ratio comparable to a primate's. It is also nocturnal, easily bullied, sensitive to medication, and sold routinely into bright community tanks.
Quick profile
- Scientific name
- Gnathonemus petersii
- Adult size
- 23–35 cm (9.1–13.8 in)
- Lifespan
- 6–10 years
- Temperature
- 23–28 °C (73–82 °F)
- pH
- 6–7.5
- Hardness
- 2–12 °dGH
- Minimum tank
- 250 L (66 US gal)
- Minimum length
- 125 cm
- Swimming zone
- Bottom
- Social
- Solitary and territorial
- Diet
- Insectivore
- Overall confidence
- low confidence
What keeping this species involves
Nocturnal, wild-caught, medication-sensitive, dependent on live food and on a soft substrate, and intolerant of its own kind in small numbers. Every one of those is routinely unmet.
Turbid, slow, muddy-bottomed rivers with abundant cover, active largely at night.
Identity and names
- Common name
- Elephantnose fish
- Scientific name
- Gnathonemus petersii
- Family
- Mormyridae
- Order
- Osteoglossiformes
- Class
- Actinopterygii
- Also sold as
- Peters's elephantnose, long-nosed elephant fish, Gnathonemus petersii
Adult size and growth
23–35 cm (9.1–13.8 in) — Commonly reaches around 25 cm in aquaria; larger in the wild.
Typical lifespan in an aquarium: 6–10 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 25 cm fish that hunts by electrolocation needs room to move without its field constantly overlapping tank walls or another individual's.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 23–28 °C (73–82 °F) | Stability matters more than hitting an exact figure. |
| pH | 6–7.5 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 2–12 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 250 L (66 US gal) | A floor, not a recommendation. |
| Minimum footprint | 125 cm long | A 25 cm fish that hunts by electrolocation needs room to move without its field constantly overlapping tank walls or another individual's. |
| Water flow | low | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Soft sand it can probe with the trunk-like chin, dim light, and caves. The chin is the sensory and feeding organ, and sharp substrate damages it. |
Behaviour
- Emits a continuous weak electrical discharge used for navigation and for communication with others of its kind.
- Probes soft substrate with the flexible chin extension, which is a modified lower jaw rather than a nose.
Feeding
Feeds after dark by probing the substrate. It rarely takes dry food and is easily outcompeted by daytime feeders.
- Diet type
- Insectivore
- Staples
- Live and frozen bloodworm, Live blackworm, Frozen mysis
Breeding
- Strategy
- Not achieved in home aquaria; commercial stock is wild-caught
- 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 | moderate | 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 | 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.
- Sensitive to many common medications and to copper. Standard doses are not safe to assume.
- Kept in twos or threes the dominant fish harasses the other continuously, and the conflict is partly electrical so cover does not fully resolve it.
- Nocturnal and easily starved in a community tank where food is gone before it emerges.
- Almost entirely wild-caught, with no established captive breeding to fall back on.
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
- Rivers of West and Central Africa, including the Congo and Niger basins
- Habitat
- Turbid, slow, muddy-bottomed rivers with abundant cover, active largely at night.
What the checklists say
5 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 | 2 | 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 | Gnathonemus petersii | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Rivers of West and Central Africa, including the Congo and Niger basins | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 23–35 cm | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| lifespan | 6–10 years | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| temperature | 23–28 °C | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| ph | 6–7.5 pH | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| general hardness | 2–12 °dGH | Aquarium-literature consensus | low confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 250 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 125 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 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. 5 distribution statements held from GBIF checklists — introduced in 2 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.
Group size and social behaviour
Aggressive to its own kind through electrical interference as much as through contact. Kept singly, or in a group of five or more in a very large tank, but not in twos and threes.