Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Gnathonemus petersii

Elephant nose fish

Elephant nose fish, Gnathonemus petersiiElephant nose fish, Gnathonemus petersii
Photos by Andy Rapson


Gnathonemus: Greek, gnathos = jaw + Greek, nema = filament

General Notes:

Although these fish are capable of reaching 35cm (14ins) they are usually much less and average around 24cm (9.5 ins) when adult. Some individuals are very peaceful towards other fish and some are quite aggressive, they are all aggressive towards their own kind. If kept in a group a very large tank of 450 litres should be the minimum size. A tank with a soft substrate is mandatory because these fish will probe it for food and sharp gravel would cause damage and lead to infection which is disastrous with this species because they don't tolerate medication at all well. Never use aquarium remedies with these fish. Elephant nose fish have very good eyesight which has evolved to allow the fish to peer through murky water. They are also electrogenic and can emit a weak electrical field around themselves and which may be used in communication with each other. Elephant nose fish are very difficult subjects in the aquarium, unless you have really looked in to what is required to care for them then don't keep them. These fish are nocturnal and dislike bright lighting which will in all likelihood increase their shyness.


Wild elephant nose fish feed on insects and worms which are found in the substrate. In captivity there is a wide variance in what individuals will eat. Some individuals will even take flake food but most require live or frozen blood  worms and similar items. They are unlikely to feed in bright daylight or from the surface.


Some say that the anal fins of male and female are different, this difference if it can be seen is very slight and shouldn't be regarded as foolproof. There is no reliable method to sex these fish.


Elephant nose fish have never been bred in captivity.

Wild status

The wild status of Gnathonemus petersii is that of 'least concern' the fish is wide ranging and not facing any immediate threats. All elephant nose fish offered for sale will be wild caught and as such will be more demanding about their environment than a lot of domesticated fish species.

Information at a glance

pH: 6 - 8
dGH: 5 - 19
Temperature: 22 - 28°C (72 - 82°F)
Diet: Omnivore
Size: 35cm (14in)
Min tank size: 450 litres
Difficulty level: Very difficult
Aquarium type: Community
Swimming level: Bottom

Distribution and habitat

distribution map for Helostoma temminckii

Origin: Africa: Niger to Congo River basins

Habitat: Large and small rivers


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Osteoglossiformes
Family: Mormyridae
Genus: Gnathonemus
Species: G. petersii (Günther, 1862)

Common name:
Elephant nose fish

Synonyms: Mormyrus petersii, Gnathonemus brevicaudatus, Gnathonemus histrio