Gnathonemus Petersii “Elephantnose Fish”

gnathonemus petersii elephantnose fish

Last updated on August 20th, 2022 at 03:17 pm

Gnathonemus petersii is a species of fish endemic to West Africa. The males can grow up to six inches in length and females are slightly smaller at five inches long, with the largest specimens reaching seven or eight inches (18-20 cm) in length. The maximum weight is up to 0.17 lbs (78 grams).

Gnathonemus petersii live in the slow-flowing and heavily shaded waters of West African rivers, where they can be found hiding under submerged tree roots or other shelters during daylight hours. During the day, groups are likely to form, consisting of one male and several females.

Gnathonemus petersii are not considered endangered or threatened, but they are listed as Least Concern (LC) on the IUCN Red List due to their wide distribution in West Africa which includes Angola, Benin, Cameroon, Central African Republic, Congo Democratic Republic of Congo, Côte d’Ivoire, Equatorial Guinea, and Gabon.

Origin and description

gnathonemus petersii elephantnose fish

The elephantnose fish or Gnathonemus petersii, gets its name from the trunk-like protrusion on its snout which they use to find food. They are found in Kenya and Southern Sudan and live underground near fast-flowing streams, rivers, and lakes where prey is most abundant.

They are only found in certain parts of Africa due to the dry season that occurs at different times each year. The species is named after Johann Jakob Kaup, a German ichthyologist and comparative anatomist who first described them in 1853.

The elephantnose fish can grow up to 27cm (11 inches) long so they are quite large compared to other species of fish.

They have a long thin body that is brownish yellow with dark spots or bands along their sides and dorsal fin which can be grey, green, or red in color. It has small eyes on the side of its head and tiny teeth but it cannot bite humans at all as they do not pose a threat to us.

The female elephantnose fish lays hundreds of eggs and after they hatch, the male sometimes cares for them until they become big enough to leave him.

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They are nocturnal creatures, meaning that like most other cave-dwelling animals, they sleep during the day and go out hunting at night instead as their eyesight is poor.

Species profile

gnathonemus petersii elephantnose fish

Gnathonemus petersii is a species of fish belonging to the Mormyridae family. They are commonly referred to as elephantfish or common weakfish and can be found across sub-Saharan Africa in freshwater rivers and lakes, where they feed on small invertebrates living among submerged vegetation. These elephantfish are not to be confused with the African elephants which also roam the continent, and get their name from a fleshy structure on top of their heads called an illicium (Latin for “fishing rod”).

The size of these fish varies greatly depending on sex. Males typically grow up to 51cm long while females only grow up to 36cm.

The species is also known as Peters’ elephantnose fish or the common elephant-snout fish. It’s a type of freshwater African catfish, native to the Congo River Basin in Africa and inhabiting swamps and wetlands.

Common name

The common name of Gnathonemus petersii is Elephantnose Fish or Peters’ elephantnose

Color and appearance

gnathonemus petersii elephantnose fish

The color ranges from gray to brown with lighter colored spots along the body. It has a distinct white bar that extends through both eyes and tapers off near the tail.

Male specimens are larger than females, have more elongated snouts, smaller mouths, longer dorsal fins, posteriorly placed pelvic fins that lack spines in males but do in females, and more teeth on the pharyngeal bone.

Female specimens are smaller than males, have a slightly shorter snout with the white bar extending through both eyes to form an inverted “V” shape in front of their mouth. They also lack barbels around their mouth as males do.

Their dorsal fin is located far posterior on their bodies, while the pelvic fins are located anteriorly on the body. They have two separate dorsal fins which vary in length between individuals of different sexes and ages.

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Adult males possess a modified anal fin called an “aponium”. This organ is thought to play a role in reproductive behaviors such as courtship or combat with other males for dominance.

The fish possesses a fleshy structure on top of its head called an illicium (Latin for “fishing rod”). This is used to lure prey into range, and may also be involved in courtship behaviors.

Range and habitat

Gnathonemus petersii is a freshwater fish native to the Congo Basin in Africa and inhabits swamps and wetlands.

They prefer slow-moving water with submerged vegetation such as reeds or papyrus for cover due to their weak swimming abilities. They are also known to form small schools which move through river channels at night into flooded grassland or forest to feed.

The range of these fish is limited to the Congo River Basin in Africa, which includes parts of Angola, Burundi, Cameroon, Central African Republic (CAR), The Democratic Republic Of The Congo (DRC), and Gabon. They are also found in Lake Tanganyika along with other Mormyridae species.

They are found in swamps and wetlands, where they feed on small invertebrates living among submerged vegetation. They typically dwell at depths of 15-20 meters or more but can be found as shallow as 12m during the dry season when water levels recede. These elephantfish are not to be confused with African elephants which also roam the continent.

Gnathonemus petersii size

Gnathonemus petersii reaches a maximum length of 51cm for males, while females only grow up to 36cm.

Adult male specimens are larger than female specimens and have more elongated snouts with smaller mouths. In addition, they also possess longer dorsal fins, posteriorly placed pelvic fins which lack spines in males but do in females, and more teeth on the pharyngeal bone.

Tank size

Gnathonemus petersii are not recommended for aquariums because they are considered very poor swimmers. They will typically remain in one spot when swimming, which can cause them to swim into the glass if given enough space.

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Due to their ability to breathe atmospheric oxygen, these elephantfish would ideally require an open-top tank with low flow. They are also known to jump, so their tanks must be covered securely with a lid or at the very least have no open gaps for them to escape through.

Even if it is not possible to accommodate these elephantfish in an aquarium tank, they can still make interesting pets when housed in large aquariums with other species that require similar conditions.

Elephantnose fish life cycle

It is viviparous and the breeding season in southern Africa is December to January. Females generally give birth to 20 or 30 young, but it has been documented that they can produce up to 50 offspring at a time. The length of gestation period lasts for six months (180–240 days).


This species tends to be territorial, with the territory size varying depending on food availability. They are mostly nocturnal, but can also be active during the daytime if there is sufficient food available. This species has a very interesting feeding behavior in which it uses external digestion to extract nutrients from prey items that have hard outer coats or shells (e.g., crabs).

Are they aggressive or peaceful?

Despite their largemouth and fangs, these fish are quite peaceful. They tend to only bite if they feel threatened or startled by a sudden movement.

Gnathonemus petersii care

gnathonemus petersii elephantnose fish

They are not as easy to keep as other fish because they need a lot of space and special care. They can be housed in aquariums that provide at least 50 gallons (200 L) of water per fish, preferably with several hiding places available for each individual.

Gnathonemus petersii diet

They mainly feed on small insects and their larvae, such as fruit flies (Drosophila melanogaster), pinhead crickets (Acheta domesticus), and mealworms. They also eat snails in the wild – one of the reasons they are considered a pest species by snail farmers. In captivity, they readily accept live food, such as blackworms (Lumbriculus variegatus), glass worms (Eisenia fetida), and bloodworms (Chironomus).

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Tank mates

Gnathonemus petersii is best kept alone, though it may cohabit with other species without problems. They can be very territorial and will fight over hiding places and food.

Water conditions

Water in the aquarium should be clean and well filtered. They prefer soft water with a pH of around neutral. A temperature between 24°C and 28°C is suitable, though they can also tolerate higher temperatures.

Gnathonemus petersii breeding

gnathonemus petersii elephantnose fish

Gnathonemus petersii is not easy to breed in captivity, though some people have done it successfully. The fish are usually kept with the sexes separated and then conditioned on live food before being placed together for spawning – they eat their eggs if given the chance! The eggs are typically laid on the aquarium glass or plants, with no further parental care.

Gnathonemus petersii lifespan

In the wild, they can live over 20 years. In captivity, it is likely to be shorter – around 15 years.

Parasites and diseases

They are susceptible to protozoan parasites such as Hexamita and Chilodonella, but otherwise very hardy.


Common predators of the species in the wild are Nile crocodiles (Crocodylus niloticus) and humans.

Does it make good pets?

Gnathonemus petersii is not easy to keep but is generally considered an interesting species for the experienced aquarist.


Gnathonemus petersii is a mouthbrooding species of fish from West Africa. It lives in large rivers and can be kept in captivity with some care, but needs a lot of space and special conditions to thrive.