Taxonomy & naming
Myomyrus pharao was described by the Belgian ichthyologists Max Poll and Jacques Taverne in 1967. It belongs to the family Mormyridae, the elephantnoses and mormyrids, within the order Osteoglossiformes, the bonytongues — a scattered, ancient radiation of freshwater fishes found today on four continents and united by a toothed basihyal (the "bony tongue") that occludes against toothed plates on the roof of the mouth. Mormyridae is by far the largest family in the order, concentrated in Africa, and the Congo Basin alone holds well over a hundred mormyrid species, more than half the family's known diversity.
The genus Myomyrus is one of several mormyrid genera whose names are built from myrus, a suffix drawn from Mormyrus, the family's type genus, combined with a descriptive Greek prefix; the exact intent behind this particular combination is not recorded in the sources reviewed here. The species epithet pharao is Latin for "pharaoh", after the rulers of ancient Egypt, though the reasoning Poll and Taverne had for the name is not documented in the material consulted. The type locality is Kinsuka on the Congo River, downstream of Kinshasa in the Democratic Republic of the Congo. The Catalog of Fishes treats Myomyrus pharao as a valid species.
Morphology
Myomyrus pharao has the elongated, laterally compressed body typical of many mormyrids, with a long anal fin set well back on the body and a small, narrow, weak-toothed mouth suited to picking rather than crushing prey. As in all mormyrids, a large electric organ lies in the caudal peduncle, generating a weak, pulse-type electric field, and the skin over much of the body carries electroreceptors that read distortions in that field as objects and other fish move through it.
Mormyrids as a group are known for an unusually large cerebellum relative to body size, among the highest brain-to-body ratios of any fish, an adaptation credited to the constant processing load of electrolocation. Reported maximum size for Myomyrus pharao is on the order of 11.8 in (FishBase lists roughly 11.7 in), a mid-sized mormyrid, considerably smaller than the roughly 17.7 in reached by species in the related genus Mormyrus. Many mormyrids look broadly similar to one another and are reliably told apart only by the waveform of their electric organ discharge, so external identification of preserved or photographed specimens should be treated with some caution.
Habitat
Myomyrus pharao is known from the lower Congo River, including records around Kinsuka near Kinshasa and near Wagenia Falls, in the Democratic Republic of the Congo. The lower Congo is one of the most distinctive river stretches in the world, a stretch of rapids, deep channels and rock-strewn gorges quite unlike the sluggish blackwater habitats often associated with mormyrids, and it has produced a wealth of narrow-range endemic fishes.
Water in the Congo Basin's river and floodplain habitats that the species occupies is generally soft to moderately hard, close to neutral pH, and warm, and often stained dark with dissolved tannins and suspended sediment. That dim, low-visibility water is exactly the setting in which a weak electric sense pays off: sight is of limited use, and the fish reads its surroundings, and other mormyrids, through the electric field instead.
Feeding
Mormyrids in general are carnivorous invertivores, and the small, weak-toothed mouth of Myomyrus pharao points to the same diet: aquatic insect larvae and other small invertebrates picked from the substrate and among cover, located as much by electrolocation and touch as by sight. Detailed dietary study of this particular species has not been documented in the sources reviewed here, and the specifics of its wild feeding ecology should be considered data-sparse.
Mormyrids as a family typically forage most actively at night or at dusk, when their electric sense gives them an advantage over sight-hunting fish, probing sand and debris for buried prey rather than chasing it in open water.
Mating
Courtship and species recognition in mormyrids run through the electric organ discharge: each species produces a distinctive pulse waveform, and individuals are thought to use that signal, along with rhythm changes during encounters, to identify potential mates and rivals in water too dark or turbid for visual cues to work well. Beyond that general pattern, which applies across the family, no species-specific account of courtship behaviour in Myomyrus pharao has been documented in the sources reviewed.
Mormyrid reproduction generally tracks the seasonal rise and fall of African river systems, with spawning triggered by flood conditions rather than occurring year-round, but the fine detail for this species is not established.
Breeding
Breeding biology in Myomyrus pharao, as in the great majority of mormyrids, is poorly known. Wild reproduction is believed to be a seasonal, flood-triggered event, and some mormyrids are thought to scatter or guard eggs among vegetation, but the details for this species specifically have not been worked out and should be treated as unresolved rather than assumed.
Captive breeding of mormyrids as a group is rare and largely undocumented, and there is no record in the sources reviewed of Myomyrus pharao having been bred in an aquarium. Anyone keeping the species should expect to observe, at best, incidental spawning behaviour rather than a repeatable breeding protocol.
In the aquarium
Myomyrus pharao is not an established aquarium fish; it is a narrow-range Congo Basin endemic that essentially does not appear in the hobby trade, and this account should be read as a description of the species rather than a care guide built on hobbyist experience. What follows draws on general mormyrid husbandry knowledge, which applies broadly across the family. Mormyrids as a group want soft, slightly acidic to near-neutral, warm water, dim lighting, and plenty of cover such as driftwood and leaf litter to feel secure, since they are naturally shy, largely nocturnal fish that rely on their electric sense rather than bright, open surroundings.
Mormyrids are notoriously sensitive to poor water quality and to many common medications and treatment chemicals, including copper-based products, so stable, well-filtered water and conservative dosing are essential rather than optional. They can also be territorial or outright aggressive toward their own or closely related species in the confines of a tank, despite being generally peaceful toward unrelated tankmates, so stocking density and tank size need to account for that. Given how little is documented about this particular species' captive requirements, anyone attempting to keep Myomyrus pharao should treat it as an experimental, specialist undertaking rather than a routine community fish.
Conservation
The IUCN Red List assesses Myomyrus pharao as Vulnerable, under criterion D2, in an assessment dated February 16, 2009. That designation reflects a restricted known range within the lower Congo River, a stretch of habitat that is unusual, biologically rich and vulnerable to disruption, together with a low to moderate estimated vulnerability to fishing pressure.
The lower Congo has been identified repeatedly as a global hotspot for freshwater endemism, and pressures such as habitat alteration, sedimentation and any development affecting the river's rapids and channel structure are the relevant long-term concerns for a species with such a confined range. No update to the 2009 assessment has been documented in the sources reviewed here.