Hot Water Fish

Elephant fish

  • Scientific name: Gnathonemus petersii
  • Common Name: Elephant Fish, Elephant Nose Fish
  • Aquarium size: 100 to 200 liters
  • Temperament: Calm
  • Temperature: 24ºC to 28ºC
  • pH: 6 to 6.5
  • Diet: Carnivore
  • Length: 23 centimeters


The elephant fish is one of the best known representatives of the family of the Mormíridos (Mormyridae).

The whole family of these fish are known as
«elephant» fish, due to a fleshy protrusion that they have under the mouth, in what we could call the fish’s «chin», which resembles the trunk of the famous mammal.

It is a peaceful fish with other species, sociable and that can be even somewhat shy, but with other fish of the same species it is territorial, even dominant with other weaker specimens.

Although at first glance the most striking thing about this species is its morphology, it is a fish that
it hides many and curious characteristics, such as its great intelligence, which makes it capable of learning tasks.


Its size in the aquarium rarely exceeds 23 centimeters, although in the wild it can be about 35 centimeters long.

As I have commented, the most striking thing about their morphology is the protrusion that they have under the mouth, like a trunk.

This bulge called
schnauzenorgan , they use to search the bottom of rivers and find their prey. It has tactile receptors and it is believed that even taste.
It is an elongated and laterally compressed fish, with a fork-shaped tail fin with a fleshy peduncle.

The anal and dorsal fins located far back are the same size, highly developed and appear almost symmetrical.

Another peculiarity of this curious fish is that
It does not have scales, so it is very sensitive to certain aquarium chemicals, such as medicines, salt, even the quality of the water .

Its coloration is
brownish to a very dark anthracite gray, almost black. It has white bands shaped like parentheses on the back of the body, at the height of the caudal and anal fins. The rear bands are somewhat smaller and the front bands are larger and thicker.

The fins have a whitish edging.

The electrical impulses of the elephant fish

The elephant fish produces small electrical impulses, which create an electric field around the fish . The electricity is generated thanks to a muscular tissue that it has in the caudal peduncle.

These impulses help it to
avoid obstacles in the dark, to chase live prey in cloudy water or at night, as well as to recognize other individuals of its species, find a mate and orient itself.

If you haven’t figured it out yet, his vision is rather bad.

Sexual dimorphism

There are no obvious differences between male and female elephant fish , although some aquarists suggest that it is possible to identify them by differences in the anal fin, although this has not been proven.

Yes, differences can be found between the electrical fields produced by females and males, but it is evident that it is impossible to detect it by an eye exam.

Distribution and habitat

They come from Africa, where they can be found in Mali, Benin, Nigeria, Chad, Cameroon, the Republic of the Congo and Zambia.
They like rivers with abundant vegetation and slow waters, with muddy bottoms and little visibility.

Aquarium conditions

If we want to recreate its habitat of origin, we need an aquarium with a profusion of both bottom and floating plants , which serve as a filter for the aquarium light, which should be rather dim.

We must provide them with places to hide, with
aquarium rocks, logs and roots.
The bottom of the aquarium should be sandy, as they like to search for their prey in the sand. They rummage and dig, if we put an aquarium substrate with stones, it will hurt them and if they cannot move the bottom, they will be frustrated.
The minimum size of the aquarium should rotate in the environment of 100 to 200 liters (better large) for a copy, if we are going to have more than one copy, we must go to 300 or 400 liters.

Water quality

They are fish that need the quality of the water to be optimal, they are very sensitive when the concentration of nitrates is high, causing them to make a greater number of discharges, and they can contract fungal diseases.

  • Water temperature between 24ºC and 28ºC
  • pH between 6 and 6.5
  • Hardness between 5º and 10º GH


One of the great challenges to keep the elephant fish in the aquarium is in its diet , which is very specialized . In nature, they eat mostly live prey, small crustaceans, invertebrates and enchytraeids (worms).

In the aquarium and once adapted, they will
take almost any type of dry or live food: tubifex, daphnia, scales, granules and all kinds of freeze-dried food.

Their habits are nocturnal, although they can sometimes be active during the day.
This means that
we should feed them at the end of the day, when they are most active.

As I mentioned before, they are quite blind, their way of orienting themselves is by the electrical impulses that it generates.

This means that
they are very bad at competing for food. In a community aquarium you will have to be very aware that it receives the correct diet, and that it does not have to compete with other fish.

Behavior and compatibility

They tend to be most active at night, when they have no problem getting their bearings.
They are quite calm and rather shy. They have no problem sharing space with other species.

with other congeners it can become territorial, and aggressive.

In a group there is usually a dominant male, who tends to harass the weaker specimens.

They like to swim at the bottom of the aquarium, like cobitids.


So far reproduction in the aquarium has been impossible, although it is comforting to know that its life expectancy is about 5 years.

According to some scientific studies, it may be that the fact that fish of the same species recognize each other through electrical impulses, and that they use this form of orientation to find a mate, may be diminished within the aquarium, and that is why until now it has been impossible to reproduce.

Elephant fish images

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