Product Details

African Freshwater Dolphin – Mormyrus longirostris

Overview:

The African Freshwater Dolphin is a remarkable mormyrid fish with a long, streamlined body, extended snout and an intelligent, searching feeding style. Despite the friendly trade name, Mormyrus longirostris is not a community novelty fish; it is a large, sensitive, weakly electric predator that needs a spacious, mature aquarium, soft substrate and carefully chosen tank mates. Small specimens are fascinating to grow on, but this species should only be considered by experienced aquarists with room for a very large African oddball fish.

Key Identification:

Common Name: African Freshwater Dolphin
Other Names: Freshwater Dolphin Fish, Eastern Bottlenose Mormyrid, Long-snouted Elephantfish, Bottlenose Mormyrid, Dolphin Mormyrid
Scientific Name: Mormyrus longirostris
Fish Type: Mormyrid / Elephantfish-type Predator
Water Type: Freshwater

Natural Range & Habitat:

Mormyrus longirostris is native to parts of eastern and southern Africa. FishBase records it from systems including the lower and middle Zambezi, lower Sabi and Ludi rivers, the Luapula–Moero–Bangwelo system, Tanzania’s Ruvuma and Rufiji rivers, and lakes Malawi, Tanganyika and Rukwa.

In the wild, it is associated with quiet deep water, muddy areas, caves and weed beds, often using its specialised electrical sense to locate food in low visibility. FishBase notes that it favours soft muddy bottoms, hides among weeds and forms shoals.

Appearance & Adult Size:

The African Freshwater Dolphin has a long, laterally compressed body, a gently arched back, a pointed snout and a distinctive mormyrid shape that gives it the “dolphin” trade name. Colour is usually grey, brown, bronze or olive, helping the fish blend into shaded, muddy habitats. The snout is used to probe soft substrate for food, so sharp gravel is unsuitable.

This is a large species. FishBase lists a maximum size of around 75 cm standard length and a maximum weight of 10 kg. Aquarium specimens may not always reach that full size, but they should still be planned for as very large, heavy-bodied adult fish.

Aquarium Suitability:

This species is best suited to a very large, mature aquarium or specialist oddball setup. It needs a broad footprint, subdued lighting, soft sand, open cruising space and secure hiding areas. It is not suitable for standard community aquariums, small tanks, sharp gravel, aggressive cichlid setups or aquariums with fast, competitive feeders.

Because mormyrids use weak electrical signals for navigation and communication, avoid mixing with other electric fish such as knifefish, elephantnoses or other mormyrids unless the aquarium is exceptionally large and the species are chosen with expert care.

Recommended Aquarium Size:

A practical minimum is 750 litres for a growing juvenile, with 1,000 litres or more strongly recommended for long-term adult care. A tank length of 240 cm or more is a sensible target for adult specimens. This fish is often imported at a small size, but it should be bought only by aquarists who can provide the space it will eventually need.

Water Conditions:

Temperature: 24–28°C
pH: 6.5–7.5
Hardness: Soft to moderately hard; stable conditions are more important than extremes
Additional Notes: Provide excellent filtration, high oxygenation and regular large water changes. Keep nitrate low and avoid sudden changes in chemistry. Aquarium trade sources for Mormyrus cf. longirostris give similar tropical care around pH 6.5–7.8 and 76–82°F, with very large aquarium requirements.

Temperament & Tank Mates:

Aquarium Category: Semi-Aggressive

African Freshwater Dolphins are predatory and may eat small fish, fish eggs, crustaceans and other small aquatic animals. FishBase records a diet including insects, small fishes, fish eggs, bloodworms, small crustaceans and molluscs.

Suitable tank mates are limited to large, peaceful, non-electric fish that will not fit in the mouth and will not bully or outcompete the mormyrid. Possible companions in a very large aquarium include large peaceful characins, robust African river fish, large Synodontis, suitable plecs and calm large cichlids that do not harass bottom-dwellers.

Avoid small fish, shrimp, aggressive cichlids, fin-nippers, very fast feeders and other weakly electric fish. Keep singly unless a very large specialist aquarium is available. Some mormyrids can be intolerant of close relatives, and expert mormyrid sources caution that members of this group can be quarrelsome with similar fish when kept in small numbers.

Feeding:

This is a carnivorous to omnivorous forager that needs a varied, protein-rich diet. Offer earthworms, bloodworm, chopped prawn, mussel, white fish, krill, river shrimp, blackworm where available, and high-quality sinking carnivore pellets once accepted. Many individuals feed best at dusk or after lights dim. Newly imported specimens may be shy and may need live or frozen foods before switching to prepared foods.

Do not rely on flakes or generic pellets alone, and do not use feeder fish as a routine diet because of disease risk and poor nutritional control.

Behaviour in the Aquarium:

The African Freshwater Dolphin is a bottom-to-midwater oddball that searches deliberately over soft substrate, using its snout and electrical sense to locate food. It may hide during the day and become more active in low light. It can be shy when newly introduced, so provide cover, dim lighting and a calm routine. In large, settled aquariums, it can become an impressive and intelligent display fish.

Care Notes:

Soft sand is essential to protect the snout and allow natural feeding behaviour. Avoid sharp stones, rough gravel and abrasive décor. Keep lighting subdued and provide caves, large wood or shaded areas. This species is sensitive to poor water quality and should only be added to a fully cycled, mature aquarium. Never medicate casually; mormyrids can be sensitive to some aquarium treatments, especially copper-based medications. Plan for adult size from the start and do not buy this fish as a small “oddity” for a normal community tank.

Recommended For:

Expert only

Availability:

Rare / Specialist import / Usually sold as small juveniles

Image Disclaimer:

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Natural variation in size, colour, pattern and markings can occur between individual fish.