Taxonomy & naming
Petrocephalus hutereaui was described by the Belgian-British ichthyologist George Albert Boulenger in 1913, originally as Marcusenius hutereaui, before later work reassigned it to Petrocephalus Marcusen, 1854. Both genera sit within Mormyridae, the elephantnoses and mormyrids, in the order Osteoglossiformes — the bonytongue fishes, one of the oldest surviving lineages of teleosts, named for a bony, toothed structure on the tongue that bites against toothed plates on the roof of the mouth.
The type locality is the Uele system in the middle Congo River basin, Democratic Republic of the Congo, and the species is known only from that river system. The genus name Petrocephalus comes from the Greek petros (rock, stone) and kephale (head), describing the hard, blunt skull typical of these fish — a build shared across the several dozen small African species now placed in the genus.
Morphology
Petrocephalus hutereaui is a small mormyrid, reaching about 2.5 in in total length according to FishBase — among the smallest members of a genus already made up of modestly sized fish. Like other Petrocephalus, it has a compact, rounded head and a small, downturned mouth rather than the elongated, trunk-like chin barbel (the schnauzenorgan) that identifies the related genus Gnathonemus.
As in all mormyrids, an electric organ near the base of the tail generates a weak, pulse-type discharge that the fish reads through electroreceptors distributed over its skin, using the resulting field to navigate and locate prey in low-visibility water. No electric organ discharge waveform has been published specifically for Petrocephalus hutereaui. Studies of related Petrocephalus species elsewhere in Africa have found the discharge to be triphasic and species-specific enough to separate visually similar species that are otherwise difficult to tell apart by external anatomy alone, but that work has not been extended to this species.
Habitat
Petrocephalus hutereaui is known from the Uele system, a tributary network of the middle Congo River basin in the Democratic Republic of the Congo. The species has apparently not been recorded outside this drainage, and it is treated as endemic to the Uele system rather than more broadly distributed across the Congo basin.
FishBase classifies it as a freshwater, tropical, demersal (bottom-associated) fish, consistent with the benthic habits typical of the genus. Beyond that broad classification, the published record does not specify substrate, current, depth, or water chemistry for this species, and no temperature or pH range has been documented.
Feeding
No species-specific dietary data has been published for Petrocephalus hutereaui. Mormyrids as a group are bottom-foraging invertebrate feeders that use their electric sense to locate small prey — insect larvae, worms, and tiny crustaceans — hidden in mud, silt, and leaf litter, and there is no reason to expect this species to differ, but that expectation has not been confirmed by direct observation or gut-content analysis.
Mating
Courtship and mating behaviour in Petrocephalus hutereaui have not been described. In mormyrids generally, the electric organ discharge is thought to carry information beyond navigation — sex, individual identity, and species recognition among them — and some research on other Petrocephalus species (in West Africa's Upper Volta system) has used discharge characteristics such as pulse duration and dominant frequency to distinguish otherwise similar species living side by side. Whether discharge-based signalling plays any role in courtship for this particular species is unknown; nothing has been published on its reproductive behaviour in the wild.
Breeding
There is no published record of Petrocephalus hutereaui breeding, in the wild or in captivity. Breeding biology across Mormyridae as a whole is poorly documented and rarely achieved in aquaria, and this species — known from a single river system with no history in the trade — has no spawning account of any kind to draw on. Any description of its reproductive mode would be invention rather than fact.
In the aquarium
Petrocephalus hutereaui has no documented presence in the aquarium trade; unlike some Petrocephalus and Marcusenius species that occasionally reach hobbyists, this species does not appear to have been kept or offered commercially. Any care guidance is therefore necessarily extrapolated from the family rather than drawn from experience with this fish specifically.
Mormyrids in general do best on a soft, fine substrate they can probe with their sensitive snout, in dimly lit tanks with ample cover, and in stable, clean water — the group is notably sensitive to poor water quality and to a number of common aquarium medications, so cautious acclimation and conservative dosing matter more here than with most fish. Live or frozen invertebrate foods offered after dark, matching the family's nocturnal foraging habit, are the standard approach for mormyrids that do reach the trade, but none of this has been tested against Petrocephalus hutereaui itself.
Conservation
The IUCN Red List assesses Petrocephalus hutereaui as Data Deficient, based on a 2009 assessment. The designation reflects how little is known about the species rather than evidence of decline: it has been recorded only from its type locality in the Uele system, and no information on population size, trend, or specific threats has been published.
No conservation actions specific to this species are documented. As with other narrow-range fish restricted to a single Congo basin tributary system, habitat degradation or water-quality change in the Uele system would be the general category of concern, but there is no assessment evidence to say whether such pressures are currently affecting it.