Elephantnose fish (Gnathonemus petersii)

Elephantnose fish (lat. Gnathonemus petersii) is a freshwater fish species of Mormyridae family. The fish got its specific name in honor of German zoologist Wilhelm Peters (1815—1883). It looks quite unusual due to construction of its mouth that is a trunk-like and resembles elephant’s nose. This fish species requires special tank conditions and therefore it’s not recommended for beginner aquarists.

Habitat in the wild

The fish is widespread in central and western part of African continent (Niger River, Ogun River and Chari River). It dwells in near bottom layer of muddy waters, prefers areas with slow water flow and thickly growing plants.

This is a bottom-lying fish that lives near bottom and looks for food by means of the long protrusion on its head.

Besides, the fish has developed an unusual quality – this is a weak electric field by means of which it performs spatial navigation, looks for food and communicates with its relatives.

The fish feeds on insects and various small spineless species, which it can find in the bottom substrate.


In the wild can grow up to 35 cm long, but in captivity its size as a rule doesn’t exceed 25 cm. Its lifespan in a tank is about 7-10 years.

The body is elongated and flattened from sides. It doesn’t have abdominal fins, the pectoral ones are rear, dorsal and anal fins are symmetrically located almost near the forked caudal fin base. The place where the body joins with the tail fin is very thin.

The fish distinctive feature is its ‘mouth’ namely its ‘trunk-like’ underlip, that makes it look like an elephant.

This organ has lots of nerve endings and can produce low electrical pulses that allow the fish to navigate in muddy water, find food, a partner and identify hazards.

The body coloring is dark-brown almost black and at certain lighting it can opalize with violet tint. Two light colored roundish arc-shaped lines connect dorsal and anal fins from both sides.

Difficulties in keeping

The fish is demanding in terms of keeping, since elephantnose fish requires ideal water parameters and it is very sensitive to medicines and toxic substances content in the water.

Besides, this is a timid fish, it becomes active in the evening and at night and it is demanding in terms of feeding.

Care and keeping in the tank

Scientific NameGnathonemus petersii
Common NameElephantnose fish, elephant fish, dolphin nose fish, long nose elephant fish, peters elephant nose
Tank size44 gallons and more
DietOmnivorous bottom feeder
Temperature23-28 °C (73,4-82,4°F)
Sizeup to 10 in (25 cm)
Lifespanup to 10 years

It’s good to keep this fish in a school of at least 3-4 species, but it’s even better when there are 5-7 ones. In a large school the fish feels more comfortable and tends to demonstrate aggression more seldom.

Therefore, optimal number of the species in a school is 4-7, if you keep just two of them, then the alpha male may behave very aggressive continuing until death of the weaker fish.

When there are 7 fish species in a school they demonstrate more friendly and peaceful behavior provided with enough space and sufficient number of shelters in a tank.

The fish requires a roomy tank – from 200 liters (44 gallons) capacity. The larger the fish school is, the larger should be the tank. The light should be dim and not bright to make the fish feel safe.

The fish needs shelters, at that their number should be equal or exceed the number of species in a tank. Smooth stones, snags and tank plants that can live at the conditions of low lighting, such as anubias, fern of Microsorium kind – all these can serve as shelters.

Sand or other soft substrate will do as the bottom one, otherwise the fish may damage its trunk-like underlip which will make feeding it difficult. The tank should have a lid, since the fish may jump out of the water.

In the wild this fish is active at night or in the evening, therefore it is important that the tank light is dim – the fish can’t stand bright light. Semidarkness, lots of shelters where the fish will stay during the day and come out sometimes to feed or to swim – there are all the conditions the fish requires.

The fish is very sensitive to water composition change and because of this it’s not recommended for inexperienced aquarists as well as it can’t be kept in tanks where tank water parameters aren’t stable. Like other ganoid species, elephantnose fish is sensitive to most tank chemicals including salt.

The fish is also sensitive to ammonia and nitrates content in the tank water considering that these tend to accumulate in the bottom substrate and the fish is a near bottom dweller.

Using powerful external filter is a must as well as weekly water renew and cleaning the bottom substrate, you should also control ammonia and nitrates content in the water.

Tank water temperature should be +23…+28 °C (73,4-82,4°F), dGH 5-15 °, pH — 6,0-7,5. Filtration and aeration are required, again the fish is very sensitive to the water quality, one third of which you have to renew every week.


Elephantnose fish feeds mainly on insects and their larvae which it can find on the bottom. That’s why you should feed it first of all with bloodworm and tubifex.

Some species can eat frozen and artificial food as well as well, but still you should give preference to live food.

You have to take into account the fact that elephantnose fish eats slowly, therefore don’t keep it together with fast and omnivorous species, because they can eat its food.

The fact, that the fish is trustful is particularly noteworthy, because in time you may train it to eat from your hands. One of the main criteria when feeding the fish is that this is a nocturnal species and that’s why you should feed it either after you turn off the lights or shortly before this.

Tank mates

This is calm and peaceful, but territory depended species. It is compatible with almost any tropical species, however if there isn’t enough space intraspecific fights in the tank are inevitable.

The fish shouldn’t be kept with very active or aggressive tank mates, since it won’t be able to compete with them during the feeding process.

Gender differences: male vs female

It is unknown how to tell between the male and female. They have quite little pronounced dimorphism.

It is considered that elephantnose females are larger and they have more rounded abdomen.


For now there had been no recorded successful cases of breeding in a tank.

Therefore this fish isn’t bred in captivity and all the species you see on sale were caught in the wild.

About author: Sergey Schulz

Sergey is a founder and author of Meethepet.com. He’s been fond of aquarium husbandry since his early childhood. His favorite aquariums are biotopes (Amazon River), with Echinodorus and freshwater angelfish. However, through the years he’s had experience of keeping almost all types of freshwater fish and shrimps.