Taxonomy & naming
Marcusenius livingstonii was described by the Belgian-British ichthyologist George Albert Boulenger in 1899. It sits in the family Mormyridae — the elephantnoses and mormyrids — within the order Osteoglossiformes, the bonytongues, one of the most ancient lineages of living ray-finned fish and a group scattered by deep time across South America, Africa, Southeast Asia and Australasia. The genus Marcusenius is a large, mostly West and Central/East African mormyrid genus whose species are frequently difficult to separate on external appearance alone and are more reliably distinguished by their electric-organ discharge (EOD) waveform, a detail that is largely unstudied for this particular species.
The species epithet livingstonii honours Charles Livingstone, brother of the explorer David Livingstone, who collected the type specimen. The type locality is the Rovuma River, which forms part of the border between Tanzania and Mozambique — placing the species firmly among the East African, Zambezi-region mormyrid fauna rather than the better-known West African (Niger, Congo) elephantnoses.
Morphology
Like other mormyrids, Marcusenius livingstonii has a laterally compressed body, a small, low-slung mouth suited to picking invertebrates off the substrate, and an elongated dorsal fin set opposite a similarly long anal fin, with a distinctly forked tail. At the base of the tail sits the electric organ, a modified muscle mass that generates the fish's signature pulse-type discharge; the discharge waveform, more than colour pattern, is what taxonomists and field workers increasingly use to tell similar-looking Marcusenius species apart.
FishBase reports a maximum length of around 11.8 in, which is large for a mormyrid genus whose species are more often encountered in the 3.9–7.9 in range. As in other elephantnoses, the brain of M. livingstonii is proportionally enormous for a fish, dominated by an oversized, richly folded cerebellum devoted to processing the constant stream of electrosensory information — the anatomical basis for the mormyrids' reputation as unusually intelligent, "thinking" fish.
Habitat
Marcusenius livingstonii is known from the east-flowing rivers of Tanzania, Malawi and Mozambique, with its type locality on the Rovuma River along the Tanzania–Mozambique border — placing it in the broader Zambezi/Rovuma drainage system of East Africa. FishBase describes it as a demersal freshwater fish of quiet river water that moves out onto seasonal flood plains to breed, a pattern typical of many African riverine mormyrids whose life cycle is tied to the annual flood pulse rather than to a fixed lake or channel habitat.
The water it lives in is freshwater, slightly acidic to neutral, soft to moderately hard, and generally slow-flowing or still rather than fast, oxygen-charged current — conditions where vision is of limited use and the electric sense does the work that eyes cannot, whether in murky flood water or simply after dark.
Feeding
This species is a benthic, invertebrate-feeding fish, taking aquatic insects, insect larvae and snails from the riverbed and among submerged debris. As in other mormyrids, feeding is thought to be largely a nocturnal activity, with the fish relying on electrolocation — reading distortions in its self-generated electric field — to detect buried or hidden prey in dark water rather than hunting by sight.
Specific dietary studies for M. livingstonii are not available, but its build and habitat are consistent with the generalist, bottom-picking invertebrate diet reported across the genus; nothing in the available sources suggests it takes plant material or larger prey as a significant part of its diet.
Mating
Detail on courtship in Marcusenius livingstonii specifically is sparse. What is documented is that the species is a seasonal breeder that moves onto flood plains to spawn, following the rise of the rivers it inhabits rather than breeding on a fixed schedule in the main channel. Across mormyrids generally, the electric-organ discharge is known to carry a courtship and species-recognition role — fish are thought to use differences in EOD waveform and pulse rate to identify and assess potential mates and rivals of the correct species — but whether or how this applies to M. livingstonii in the wild has not been specifically studied.
Given how little is documented, this account does not claim more than that: a flood-triggered, seasonal spawner whose courtship behaviour is presumed to involve the electric sense by analogy with better-studied mormyrids, but is not itself described in the literature available here.
Breeding
Marcusenius livingstonii is not known to be bred in captivity, and no farmed or commercially bred stock has been reported. This is consistent with mormyrids as a whole, which are notoriously difficult to spawn under aquarium conditions and are essentially never produced by hobbyists or commercial breeders — virtually all mormyrids seen in the trade, on the rare occasions they appear at all, are wild-caught.
In the wild, breeding is tied to the flood-plain migration described above, but the mechanics — nest building or lack of it, egg-laying behaviour, incubation time, and any parental care — are poorly documented for this species. Rather than guess, this account states plainly that captive breeding has not been achieved and the wild breeding biology remains largely unknown.
In the aquarium
Marcusenius livingstonii is rarely, if ever, offered in the aquarium trade, and this account does not overstate its availability. Where mormyrids of this general type are kept, the consensus care parameters are soft-to-moderately-hard, slightly acidic to near-neutral water (roughly pH 6.0–7.5) at 72–81 °F, a tank of at least a metre in length to accommodate an active bottom-dwelling fish of this size, and dim lighting with ample cover — driftwood, roots and leaf litter — since these are shy, largely nocturnal fish that stress under bright, open conditions.
Mormyrids as a group are notably sensitive to poor water quality and to many medications, and are best kept in a stable, well-matured tank with minimal chemical intervention. They also generally do poorly kept singly; a loose group is the more natural and lower-stress arrangement, though tankmates should be chosen carefully, since electric fish can be sensitive to disturbance from boisterous or fin-nipping species. Anyone considering this species should treat it as a specialist's fish rather than a community option, and should be confident of its wild-caught origin and the seller's husbandry before purchase.
Conservation
The IUCN Red List assesses Marcusenius livingstonii as Least Concern, reflecting its occurrence across multiple river systems in Tanzania, Malawi and Mozambique rather than a narrow, single-locality range. The assessment nonetheless flags habitat loss as a relevant pressure on the species.
As with many African riverine fish, the main long-term concerns are indirect: damming, water abstraction and land-use change along the rivers and flood plains it depends on for breeding. Because it is essentially absent from the aquarium trade, collection for the hobby is not considered a factor in its conservation status.