Taxonomy & naming
Petrocephalus stuhlmanni was described in 1909 by George Albert Boulenger, the Belgian-born zoologist who spent virtually his entire career on the fish collections of the British Museum (Natural History) in London and named more African freshwater fish species than any other author of his era. The description falls within the years Boulenger spent compiling his four-volume Catalogue of the Fresh-Water Fishes of Africa, the first volume of which appeared in 1909. It belongs to the family Mormyridae — the elephantnoses and mormyrids — within Osteoglossiformes, the bonytongue fishes, one of the oldest surviving lineages of living teleosts.
The genus Petrocephalus has been reworked substantially since Boulenger's time. Modern revisions by researchers including Sébastien Lavoué and John Sullivan use electric organ discharge waveforms together with molecular data to redraw species boundaries across the genus, because the small, rounded, largely featureless body shared by most Petrocephalus species leaves few reliable characters to separate them by eye alone. Whether that later work has revised the status of Petrocephalus stuhlmanni beyond Boulenger's original description could not be confirmed for this account; Boulenger, 1909 remains its name-bearing authority.
Morphology
As in other members of the genus, Petrocephalus stuhlmanni can be expected to share the typical Petrocephalus build: a laterally compressed, rounded body, a short blunt head, and a small mouth set low and back from the snout, without the elongate chin appendage — the schnauzenorgan — that marks the related genus Gnathonemus. Species-specific measurements were not confirmed for this account. Published figures for the genus as a whole mostly fall between about 6 and 6 in standard length, but that is a genus-wide range, not a measurement of this particular species.
Like every mormyrid, it almost certainly carries a weak electric organ near the base of the tail, paired with electroreceptors across the skin, used to sense the surroundings and locate prey in dark or turbid water. The waveform of that discharge is often the most reliable way to separate similar-looking Petrocephalus species, since many are otherwise close to identical by eye. No discharge data specific to Petrocephalus stuhlmanni could be confirmed for this account.
Habitat
Documented habitat and range details for Petrocephalus stuhlmanni — the river or lake system it inhabits, water depth, substrate, or temperature — were not available for this account, and no country or drainage record could be confirmed. Most Petrocephalus species are African freshwater fish restricted to a single river or lake basin rather than distributed across the continent, which is a reasonable expectation for this species too, but that is a genus-level pattern and not a substitute for a confirmed locality record.
Feeding
No feeding study specific to Petrocephalus stuhlmanni was confirmed for this account. Mormyrids in general are benthic invertebrate feeders, using their electric sense to locate insect larvae, worms, and small crustaceans hidden in mud, sand, or leaf litter, then taking them with a quick strike of the small, downturned mouth. No account of this species being kept or fed in captivity is documented.
Mating
Courtship and mate recognition in mormyrids are generally understood to involve the electric organ discharge, whose pulse pattern is often distinct enough between closely related species to signal species identity and, in some cases, sex. Whether that holds for Petrocephalus stuhlmanni specifically has not been studied, and no account of its mating behavior in the wild is available.
Breeding
No spawning event, wild or in captivity, has been documented for Petrocephalus stuhlmanni. Breeding across the mormyrids generally is poorly understood and rarely achieved in the aquarium, and this species has no recorded breeding history at all. Any specimens that reached the trade would almost certainly be wild-caught rather than captive-bred.
In the aquarium
Petrocephalus stuhlmanni has essentially no track record in the aquarium hobby — no documented imports, care reports, or trade presence, unlike better-known relatives such as the elephantnose fish. Should a small Petrocephalus of this kind become available, the general rules that apply across mormyrids would still hold: soft sand for probing, dim lighting and ample cover to offset weak eyesight, live or frozen invertebrate foods rather than flake, and caution with water quality and medication, since mormyrids as a group are known to be unusually sensitive to both. None of that amounts to documented experience with this particular species, which does not exist in the sources reviewed for this account.
Conservation
No IUCN Red List assessment for Petrocephalus stuhlmanni could be confirmed for this account, and its status is treated here as not evaluated rather than assumed safe. As with other narrow-range African freshwater fish, habitat degradation, siltation, and pressure on the rivers or lakes it depends on are the general threats most likely to matter, but no species-specific threat assessment is available.