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Elephantnose Fish
Gnathonemus petersii
This fascinating African micro-predator uses its highly sensitive, trunk-like appendage and an electrical organ to hunt in the mud. It demands extremely dim lighting, fine sand, and extensive hiding places.
Water Temperature
23 - 28 °C
pH Value
6 - 7.5
Water type
Freshwater
Tank level
Bottom
Adult size
23 cm
Minimum tank volume
250 L
Minimum group
>= 1
GH
4 - 15 dGH
KH
2 - 7 dKH
TDS
80 - 295 ppm
Conductivity
125 - 461 uS/cm
Species description
Geographical Origin and Habitat: Very widespread species in the river basins of West and Central Africa (Niger, Ogun, Chari rivers). Inhabits the darkness of muddy-bottomed areas, moving slowly along the banks rich in dense submerged vegetation.
Taxonomy and Morphology: Peters' Elephantnose Fish. Astounding morphology: a flexible tubular appendage similar to a trunk ("Schnauzenorgan") protrudes from the lower lip. Used as a highly sophisticated tactile sensor and electromotor organ to locate prey in the mud. Length up to 23 cm (9 inches).
Social Behavior: Nocturnal, shy and gifted with the brain with the highest mass/body ratio among fish (extraordinary intelligence, they have been trained in labs). Creates a weak electric field to echolocate. Can be extremely aggressive towards conspecifics if kept in groups too small (under 6 specimens).
Coloration and Sexual Dimorphism: Dark camouflage for the night: opaque black or dark chocolate brown body, with two bright white vertical bands between the closely spaced dorsal and anal fins. The caudal peduncle is very thin. No sexual dimorphism visible to the naked eye (distinguishable in the lab by electrical signals).
Care, breeding and tankmates
Aquarium Setup: Tank of at least 250 liters (65 gallons) with EXTREMELY dim lights (they hate bright light). It is imperative to use a bottom made only of VERY FINE SAND to protect the delicate trunk from excoriations. Provide a multitude of individual hiding places: PVC pipes, stacked smooth rocks.
Diet and Feeding: Insectivorous micro-predator. Locates and unearths larvae in the mud with electro-reception. Will hardly accept flakes. Must be fed with large portions of live or frozen bloodworms, tubifex and brine shrimp, administered in the evening when the aquarium is dark.
Water Quality: Very sensitive to pollutants. Neutral to weakly acidic water (pH 6.0-7.5) at 24-27°C (75-81°F). Filtration must be impeccable but with very little turbulence. Tolerates zero nitrites and is chronically intolerant to nitrate concentrations above 20ppm.
Compatibility and Cohabitation: Ideal with peaceful African mid-water fish (Congo Tetras, African Butterflyfish). Not recommended to pair with Cichlids or aggressive bottom fish (Botia, large Loricariids) which would bully it forcing it to starve, as it is very slow to eat.
Aquarium Breeding: Not successfully documented in home or commercial aquariums. Reproduction in nature strictly depends on the monsoonal rain cycles that radically alter the electrical and chemical parameters of the water.
Risks and Diseases: Being fish without true scales ("scaleless"), copper, malachite green and common store drugs are lethal to them. They die of starvation if placed in too bright tanks or disturbed by voracious tankmates. A wound to the trunk condemns them to the inability to feed.
Geographic Origin and Distribution
Very widespread species in the river basins of West and Central Africa (Niger, Ogun, Chari rivers). Inhabits the darkness of muddy-bottomed areas, moving slowly along the banks rich in dense submerged vegetation.
Origin
North AmericaAfrica and MadagascarEast Asia
Fish profile
- Temperament
- Semi-aggressive
- They are peaceful but somewhat shy. They rely on mild electrical impulses to navigate. Provide plenty of dark hiding spots like PVC pipes.
- Diet
- Omnivore
- Their diet is strictly carnivorous. They forage for worms and small insects in the substrate. Offer frozen bloodworms and tubifex worms regularly.
- Life expectancy
- 6-10 years
- In captivity, this species has an average life expectancy ranging between 6 and 10 years, although with optimal care and in stable tanks, it can exceed this milestone. To promote their longevity, maintaining excellent water quality with efficient biological filtration is crucial. The stability of physical water parameters is also of vital importance to limit hormonal stress.
- Adult size
- 23 cm
- The catalog's scalar value is 23 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 35 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Gnathonemus petersii (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Solitary
- Determining sex is practically impossible visually. They are best kept as solitary specimens in home aquariums. Therefore, sex ratios are generally irrelevant here.
- Feeding frequency
- Twice daily
- Feed them once or twice daily. They are nocturnal feeders by nature. Feeding them after lights out is highly recommended.
- Bioload
- Elephantnose fish produce a moderate bioload. They are relatively large and eat substantial meaty foods. Good filtration is necessary to process their waste.
- Flow
- Stagnant
- They prefer a slow to moderate water flow. Gentle currents suit their natural murky river habitats. Avoid overly turbulent water conditions.
- Reproduction
- Oviparous
- Breeding in captivity is extremely rare. They require specific environmental triggers not easily replicated. Very little is known about their captive breeding habits.
- Compatibility & tankmates
- They are generally peaceful with other species. However, they can be aggressive towards their own kind. Keep them individually unless the tank is massive.
- Tank level
- Bottom
- They inhabit the bottom level of the tank. They use their specialized chin extension to probe the sand. A soft, sandy substrate is absolutely vital.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.1 ± 0.34 se
- Resilience
- Medium (1.4 - 4.4 years)
- Phylogenetic uniqueness (PD50)
- 0.5625
- Bayesian Length-Weight
- a = 0.01259, b = 2.87
- VulnerabilityLow to moderate vulnerability (33 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
