Taxonomy & naming
Mormyrops citernii was described by the Italian ichthyologist Decio Vinciguerra in 1912, in the Annali del Museo Civico di Storia Naturale di Genova, from a specimen collected during the 1910–1911 Italian expedition that mapped the boundary between Italian Somalia and Ethiopia. The holotype (catalogued MSNG 2065) came from the upper Genale River, part of the Juba–Genale system that drains from the Ethiopian highlands through Somalia to the Indian Ocean. The species belongs to the family Mormyridae — the elephantfishes and mormyrids — a strictly African family of roughly 200 species and one of two families (alongside the monotypic Gymnarchidae) making up the order Osteoglossiformes, the bonytongues. Osteoglossiformes is among the oldest living lineages of teleost fish, its members named for a bony, toothed structure on the tongue that bites against a toothed plate on the roof of the mouth; the order's living representatives are scattered across South America, Africa, Southeast Asia and Australasia, a deep-time relict of a once far more widespread radiation.
The genus name Mormyrops combines Mormyrus — the name of a related mormyrid genus, itself derived from an old Greek name for a fish — with the Greek suffix -ops, "face" or "appearance", so the genus name reads roughly as "Mormyrus-like". The species epithet citernii honours Captain Carlo Citerni (1873–1918), the Italian officer who led the 1910–1911 boundary expedition during which the holotype was collected. As with many mormyrids described from a single historical expedition specimen, the species has been little revisited since its original description, and its relationship to other East African Mormyrops has not been closely studied.
Morphology
FishBase records a maximum size of 14 in standard length for Mormyrops citernii; total length would run somewhat longer still, putting the species among the mid-sized members of a genus that includes both compact and considerably larger river mormyrids. Beyond that headline figure, no detailed morphological account — fin-ray counts, body proportions, colour pattern — was found in the sources consulted here, and the species should be treated as poorly described outside its original 1912 taxonomic account.
Like all mormyrids, M. citernii almost certainly carries a weakly electric organ in the caudal peduncle, near the base of the tail, firing a continuous train of brief electrical pulses — the defining feature of the family and the trait every Mormyrops shares regardless of how little else is documented about a given species. A dense field of electroreceptors covers the body and reads the distortions this discharge makes as it passes over rocks, submerged wood, prey and other fish, an active sixth sense that substitutes for vision in the turbid, tannin-stained water typical of the family's African river habitats. Data on this species' precise body shape, mouth form and coloration is sparse; it should not be assumed to match better-studied Mormyrops such as M. anguilloides without confirmation.
Habitat
Mormyrops citernii is known from the Juba–Genale river system, which drains the Ethiopian highlands and crosses the Ethiopia–Somalia border before reaching the Indian Ocean — a tropical savanna river system that flows year-round but is subject to a pronounced rainy season, roughly April to June, when flow and turbidity both increase sharply. The type locality, the upper Genale River in Ethiopia, sits well upstream in this system.
As a mormyrid, it almost certainly occupies the murky, sediment-laden freshwater typical of the family, in warm tropical conditions estimated in the region of 75–82 °F, though no site-specific temperature or pH readings for this river system were found in the sources reviewed here. Detailed population data, micro-habitat preference and current range within the Juba–Genale basin are sparse; the species is known essentially from its type locality and has not been the subject of a modern survey, so its status within the wider basin should be treated as data-poor rather than confirmed.
Feeding
No species-specific dietary study of Mormyrops citernii was found in the sources consulted here. What can be said comes from the wider mormyrid pattern: like other members of the family, it almost certainly forages nocturnally, using its electric organ discharge to electrolocate prey hidden in sediment or debris rather than hunting by sight, and the diet in the wild is presumed to be the standard mormyrid fare of aquatic invertebrates — insect larvae, worms and small crustaceans — picked from the riverbed after dark.
Because this species is essentially unknown in captivity, there is no aquarium feeding record to draw on. Any captive account would need to follow general mormyrid husbandry — sinking, protein-rich foods offered after lights-out — but this remains inference from the family rather than documented experience with M. citernii itself.
Mating
Mating behaviour in Mormyrops citernii has not been documented, and being honest about that gap matters more than filling it in. What is known comes from the wider mormyrid literature: in the wild, mormyrids are generally seasonal spawners whose reproduction is tied to the rains and the flooding of river margins — a pattern that fits the Juba–Genale system's pronounced April–June wet season — and the electric organ discharge, beyond its role in foraging, is thought to double as a courtship and species-recognition signal, letting a fish distinguish a potential mate of its own species from the many other electric fish sharing the same water.
Beyond that broad pattern, courtship and pairing behaviour in this species is essentially unknown, and no observations of wild or captive spawning were located in the sources reviewed here.
Breeding
No captive breeding of Mormyrops citernii has been documented, and captive breeding of mormyrids in general is described as very difficult and only patchily understood — a handful of species have spawned under controlled conditions, but the process is not something a home aquarist can reliably reproduce, and this species has essentially no presence in the hobby to draw on. Some mormyrids are thought to scatter eggs among plants or fine root mats in flooded margins with no organised nest and little parental care beyond that, but the specifics for this species have not been studied.
Given this, the honest position is that Mormyrops citernii should be regarded as unbred in captivity and effectively unavailable to hobbyists: there is no established husbandry record, no confirmed spawning account, and no realistic expectation that a keeper could reproduce it without a great deal of luck and a very large, stable system.
In the aquarium
Mormyrops citernii has no meaningful presence in the aquarium hobby; it is not a species a keeper is likely to encounter, and no dedicated care account for it was found in the sources reviewed here. Any husbandry guidance has to be extrapolated cautiously from the wider mormyrid family rather than from direct experience with this fish, and should be treated as provisional.
Were a specimen ever to reach a tank, general mormyrid principles would apply: soft, only lightly mineralised, warm tropical water in a dimly lit setup furnished with driftwood, plants and caves, kept quiet during the day since this is a nocturnal, electrolocating fish. Mormyrids in general have electroreceptive, sensitive skin that makes them more vulnerable than average to poor water quality and to some medications — dose gently and avoid copper-based treatments where possible — and many species are territorial toward their own kind in confined spaces. At a reported 14 in SL it is a mid-sized mormyrid rather than a giant, but with essentially no husbandry track record for this species specifically, any tank should be planned conservatively and any acquisition treated as an experiment rather than a routine purchase.
Conservation
Mormyrops citernii has not been formally assessed on the IUCN Red List and is currently listed as Not Evaluated. This reflects how little modern survey work has been done on the species since its 1912 description rather than any specific evidence of population decline or stability.
The Juba–Genale river system it inhabits crosses an area shaped by decades of political instability in Somalia and by ongoing water-resource pressures in the Ethiopian highlands, both of which make systematic fish surveys difficult to carry out and sparse in the literature. Without a formal assessment or recent population data, the species' conservation status should be treated as genuinely unknown rather than assumed to be safe; data sparse is the honest summary for both its ecology and its conservation standing.