Elephantnose fish

Identity and search names

This profile applies to Gnathonemus petersii. Confirm trade identity and preserve breeder, supplier or locality records where relevant.

Environment and housing

Large dim mature aquarium with deep fine sand, wood and root refuge, multiple separated territories, low stray electrical noise and guarded equipment

Feeding and nutrition

Feeding ecology: Specialised benthic micropredator; insect larvae, worms, small crustaceans and accepted fine sinking foods

Feeding routine: Target-feed after lights dim at several sites and confirm every fish maintains body condition

Breeding and reproduction

Reliable routine aquarium breeding is not established and breeding behaviour remains poorly documented

Parental care: Insufficiently documented; do not assume an absence of care

System demands

Filtration: Use mature biological filtration sized for the adult stock and feeding load, with guarded intakes and a flow pattern the species can use without continual effort.

Aeration: Maintain strong gas exchange and stable dissolved oxygen, especially overnight, during warm weather, medication, crowding or any interruption to filtration.

Maintenance: Test ammonia and nitrite after changes or abnormal behaviour; remove waste from the occupied zone and perform regular water changes matched to temperature and mineral chemistry.

Detailed husbandry

Identity scope

This profile applies to Gnathonemus petersii. Confirm trade identity and preserve breeder, supplier or locality records where relevant.

Adult size and space

Up to about 25 cm total length. At least 600 L for a properly managed group of five or more, with a long dim footprint and extensive refuge. Plan around adult dimensions, activity, group size, aggression and waste production rather than sale size.

Social structure

Keep a properly sized group of at least five only in a very large structured aquarium; pairs and trios commonly concentrate aggression on one fish

Swimming zone

Primary zone: Species-specific. Keep that zone usable for movement, feeding and refuge.

Feeding ecology

Specialised benthic micropredator; insect larvae, worms, small crustaceans and accepted fine sinking foods

Feeding plan

Target-feed after lights dim at several sites and confirm every fish maintains body condition

Water stability

Maintain 24–28 °C; pH 6.0–7.5; hardness/minerals: Soft to moderately hard. Stable oxygenation and nitrogen-cycle control matter more than chasing one exact number.

Habitat structure

Large dim mature aquarium with deep fine sand, wood and root refuge, multiple separated territories, low stray electrical noise and guarded equipment

Compatibility plan

Quiet fish that do not monopolise bottom foods; do not casually mix with other mormyrids or electrically active equipment

Breeding plan

Reliable routine aquarium breeding is not established and breeding behaviour remains poorly documented. Parental care: Insufficiently documented; do not assume an absence of care.

Quarantine

Quarantine new fish in a separate cycled aquarium with dedicated equipment. Match temperature and mineral chemistry gradually, confirm feeding and normal respiration, and never add transport water to the established aquarium.

Welfare checks

Maintain the stated adult space and social structure, verify feeding and intervene early when injury, exclusion, weight loss, abnormal respiration or altered behaviour appears. Gnathonemus petersii is a sensory and social specialist, and 2026 morphometric work indicates a possible hidden species complex. Preserve provenance, avoid pairs or trios, use fine sand and verify every fish feeds.

Biosecurity and release

Never release fish, fry, eggs, aquarium water, sediment, plants or live foods into drains, dams or natural waterways. Confirm current Australian import conditions and South Australian possession, trade and movement rules before acquisition or transfer.

Main risk

Gnathonemus petersii is a sensory and social specialist, and 2026 morphometric work indicates a possible hidden species complex. Preserve provenance, avoid pairs or trios, use fine sand and verify every fish feeds.

Adult Projected Load

Moderate to high because adults are sensitive, intelligent weakly electric fish whose social interactions, nocturnal feeding and need for unobstructed sand increase usable-space and monitoring requirements.

Filtration

Use mature mechanical and biological filtration with protected intakes and enough turnover for the adult group while preserving species-appropriate current and refuge.

Aeration

Provide strong gas exchange and backup aeration; increase oxygen support before warm weather, heavy feeding, crowding, medication or filter interruption reduces the safety margin.

Maintenance

Remove uneaten food and bottom waste, clean prefilters before flow falls, test ammonia and nitrite after changes, and perform regular temperature- and chemistry-matched water changes.

Overridable Warnings

Hidden-species-complex risk, electrical-sensory welfare, soft substrate, low-stress social planning, night feeding and stable water cannot be overridden.

Welfare and risk

Maintain the stated adult space and social structure, verify feeding and intervene early when injury, exclusion, weight loss, abnormal respiration or altered behaviour appears. Gnathonemus petersii is a sensory and social specialist, and 2026 morphometric work indicates a possible hidden species complex. Preserve provenance, avoid pairs or trios, use fine sand and verify every fish feeds.

Sources

• Eschmeyer’s Catalog of Fishes — Gnathonemus petersii — Accepted-name, synonym and taxonomic-placement cross-check
• Catalog of Fishes reference — hidden diversity in Gnathonemus petersii — 2026 morphometric evidence for a hidden species complex
• IUCN Red List search — Gnathonemus petersii — Conservation-status and wild-provenance cross-check
• Australian Government — importing live ornamental fish — Australian import pathway and biosecurity requirements
• PIRSA — South Australian noxious fish list — South Australian possession, trade and release context
• Eschmeyer’s Catalog of Fishes current search — Gnathonemus petersii — Current accepted-name, synonym, distribution and habitat cross-check