Elephant Nose Fish
Gnathonemus petersii
Min Tank Size
200L
Adult Size
23 cm
Lifespan
10 years
About
Native to the river basins of Central and West Africa, the Elephant Nose Fish is one of the most unusual animals you can keep in a freshwater aquarium. That rubbery, trunk-like extension on its chin isn't actually a nose at all, it's a modified lower lip called a rostrum, used to root through sand and gravel hunting for worms, insect larvae, and other invertebrates buried in the substrate. They navigate and communicate using a weak electrical organ near their tail, which generates a continuous field they can sense with receptors across their skin. Research into their brain-to-body ratio has consistently surprised scientists. These fish are genuinely smart.
Keeping one successfully is a serious commitment. Water quality has to be excellent and stable, soft acidic conditions are strongly preferred, and they don't tolerate the swings that hardier fish shrug off. A sand substrate is non-negotiable since they spend a lot of time probing it with that sensitive rostrum. Caves, driftwood, and dim lighting matter too because they're nocturnal and will stay hidden and stressed in a brightly lit, open setup.
Feed in the evening with bloodworms, tubifex, or small sinking invertebrate-based foods. Frozen and live foods work better than dry for most individuals. They grow to around 23 cm and need a 200-liter tank at minimum, though larger is better.
Despite their peaceful appearance, they can be surprisingly intolerant of their own kind and other weakly electric species. When everything is dialed in, watching one probe its way across the sandbed at dusk is genuinely captivating. Browse tank builds featuring this species to see how experienced keepers set up a proper habitat.
Water Parameters
Temperature
°CpH
GH
dGHKH
dKHSwimming Level
Flow Preference
Keeping multiple Elephant Nose Fish together
Elephant Nose Fish is strongly territorial. Multiples fight over space unless the tank is large enough for each to claim its own area. A single individual is the safer default.
Compatibility
Peaceful mid and upper water column fish work well as tankmates, provided they aren't so tiny they become prey. Congo tetras are a classic pairing since they share the same African biotope and water parameter preferences. Larger rasboras, peaceful cichlids like keyhole cichlids, and robust tetras are fine options. Avoid tiger barbs and any habitual fin nippers since a stressed elephant nose is a sick elephant nose. Completely avoid other weakly electric fish. Bottom-dwellers that compete for the same territory and hiding spots, like larger loaches, can also cause problems. This isn't a community fish you drop into any setup.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
The most common failure with this species is underfeeding because keepers don't realize how nocturnal they are. If you're feeding during the day, the elephant nose may simply not be eating. Switch to evening feedings with frozen bloodworms or live blackworms and check that food is actually disappearing. The second biggest mistake is keeping them in hard alkaline water, they decline slowly and keepers often don't connect the dots until it's too late. Sand substrate, low light, multiple caves, and pristine soft acidic water are the baseline requirements, not optional extras.
Behavior & Aggression
Most of the aggression in this species is directed at conspecifics and other weakly electric fish like black ghost knifefish or other mormyrids. Two elephant nose fish in the same tank will almost always escalate into conflict, especially in smaller setups. The aggression isn't fin-nipping or chasing, it's a war of attrition where the subordinate fish gets outcompeted for food and hiding spots until it wastes away. Keep one per tank unless you have a truly massive, heavily decorated setup where sight lines can be broken completely.
Things to Know
- Highly aggressive toward other weakly electric fish, including its own species
- Very sensitive to water quality, small parameter swings can be fatal
- Strictly nocturnal, may starve if not given evening or overnight feedings
- Prone to ich and disease when stressed, avoid copper-based treatments
- Will eat small shrimp and snails by probing substrate with its rostrum
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