Taxonomy & naming
Mormyrus kannume was described by the Swedish-Finnish naturalist Peter Forsskål in 1775, published posthumously in Descriptiones animalium from the material he collected on the Danish Arabia expedition led by Carsten Niebuhr. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) treats Mormyrus kannume as the currently valid name. It belongs to the family Mormyridae within Osteoglossiformes, the bonytongue fishes, a scattered and ancient radiation that also includes the arowanas of South America, Asia and Australia, the African and Asian featherback knifefishes, and the giant arapaima of the Amazon — among the oldest surviving branches of the teleost fish tree, named for a toothed bone on the tongue that bites against a matching patch on the roof of the mouth.
The genus name Mormyrus is borrowed from the ancient Greek mormyros, a name the classical authors used for an unrelated Mediterranean sea bream; naturalists later reused it for this African freshwater genus of some sixty species. The species epithet kannume is not a Latin or Greek description at all but a Latinised form of a local East African name for the fish, recorded from the Lake Victoria region — a reminder that a fair number of mormyrid names simply preserve the word fishermen already used for the animal.
Morphology
Mormyrus kannume has the elongated, laterally compressed body typical of the genus, with a small mouth set beneath a short, somewhat downturned snout — nothing like the long, mobile trunk of the unrelated elephantnose Gnathonemus petersii, despite sharing the common-name "elephantfish" family resemblance. The dorsal fin sits well back on the body opposite a long anal fin, and the tail is deeply forked with a slender caudal peduncle. Colour is a plain silvery grey to olive-brown, without bold pattern, and the skin is scaled rather than naked.
That caudal peduncle houses the fish's electric organ, which produces a species-specific, pulse-type electric-organ discharge (EOD). The discharge is weak — far too weak to stun anything — and is read by electroreceptors spread over the head and body, giving the fish an active sense for objects, obstacles and other mormyrids in water too dark or turbid for vision to do the job. Mormyrids as a group are known for an unusually large brain relative to body size, with an enlarged cerebellum devoted to processing this electrical picture of the world, and Mormyrus kannume is a solidly built example of the family at a large adult size: FishBase records a maximum of around 39.4 in total length, with fish more typically encountered around 23.6 in.
Habitat
This is a Nile-basin fish in the broad sense. Its documented range runs from the Lower Nile in Egypt (the type locality is given as Damietta) up through Sudan and the Baro system in Ethiopia, and into the East African lakes fed by the upper Nile — Lake Victoria, Lake Kyoga, Lake Albert, Lake Edward and Lake George — as well as Lake Turkana and the Ewaso Nyiro system in Kenya. Across that range it occupies open water in rivers and lakes from the surface down to around 230 ft, a wider depth tolerance than many of its mormyrid relatives.
Water across this range is tropical and fairly warm, with FishBase citing roughly 72–79 °F, and much of the habitat is the soft-bottomed, sediment- or plankton-turbid water typical of large African rivers and lake margins — exactly the low-visibility conditions the electric sense is built to read. As a wide-ranging Nile-basin species it is not confined to one narrow catchment the way some smaller mormyrids are, but within any given water body it still favours slow water over soft substrate rather than fast, clear, rocky habitat.
Feeding
Mormyrus kannume feeds mainly on benthic invertebrates — insect larvae and worms probed out of soft sediment — locating buried prey with the electric sense rather than by sight alone, a foraging style shared across the family. Like most mormyrids it is most active around dusk and after dark, when it forages over the bottom rather than in open water.
In the aquarium it takes live and frozen tubifex worms and bloodworm readily and generally needs meaty foods of this kind rather than flake or dry pellet; it does not thrive as a grazer. Feeding after lights-out, matching its natural activity pattern, gets the best results in a tank with other, less nocturnal fish.
Mating
Courtship in mormyrids is thought to run substantially through the electric-organ discharge — the pulse pattern is species-specific and is presumed to play a role in mate recognition and dominance signalling — but the fine detail of courtship behaviour in Mormyrus kannume specifically is not well documented. What is recorded is the seasonal timing: a study of the species in the Upper Victoria Nile in Uganda found spawning activity through much of the year with a marked peak in March, coinciding with the onset of the rains, a pattern consistent with a flood-triggered spawner responding to rising water and the food pulse that follows it.
Beyond that seasonal signal, little is published on how pairs or groups actually come together to spawn, and this account does not speculate further where the record is silent.
Breeding
Captive breeding of Mormyrus kannume is essentially unreported. Aquarium-trade individuals are wild-caught, and the species is not part of the small handful of mormyrids that hobbyists have managed to spawn under aquarium conditions. What is known comes from field observation of the wild population in Uganda, which points to a seasonal, rain- and flood-triggered spawning pattern rather than a year-round or easily triggered one.
Parental care in this species is likewise poorly known. Prospective breeders should treat this as an essentially unsolved problem rather than a project with an established protocol to follow.
In the aquarium
The first fact to reckon with is size: Mormyrus kannume can reach around a metre in total length, and even a typical adult at 23.6 in is a substantial fish. It needs a long, large aquarium from the outset — recommendations run to 59.1 in and up, with more length needed to comfortably house a fish approaching full size — and buyers of a small juvenile should plan for that footprint, not assume the fish will stay small.
Water should be kept soft to moderately hard and close to neutral, roughly pH 6.5–7.2, at a warm 77–81 °F, over a soft sand substrate the fish can probe without abrading its sensitive skin and snout. Lighting should be dim rather than bright, echoing the turbid water it comes from, and the tank should offer some cover along with open swimming space. Mormyrus kannume is active and can be temperamental toward tankmates, sometimes harassing other fish, and it is frequently kept singly in the hobby rather than in company; territorial disputes between two mormyrids in the same tank are also a real risk. As with mormyrids generally, sudden changes in water chemistry and some medications are poorly tolerated, so stability and a cautious approach to treatment matter more than with a hardier community fish.
Conservation
The IUCN Red List assesses Mormyrus kannume as Least Concern, an assessment from December 2015. It is a widely distributed species across the Nile basin and the East African lakes rather than a narrow-range endemic, and no major range-wide threat is flagged in that assessment.
That wide distribution does not mean every population is immune to pressure — East African lakes and Nile tributaries face ongoing issues from fishing, water abstraction and habitat modification in places — but nothing in the available record points to a species-level decline for Mormyrus kannume specifically, and it remains categorised as a fish of least conservation concern.