Taxonomy & naming
Petrocephalus valentini was described in 2010 by Sébastien Lavoué, John P. Sullivan and Matthew E. Arnegard, in a Zootaxa revision (volume 2600, pages 1–52) of the genus Petrocephalus based on fish collected in and around Odzala National Park in the Republic of the Congo. The same paper named four other new species from the same river system — Petrocephalus mbossou, P. odzalaensis, P. pulsivertens and P. zakoni — separating them from one another and from previously known congeners with a combination of body proportions, fin-ray counts, pigmentation and the waveform of the electric organ discharge (EOD). Petrocephalus valentini belongs to the family Mormyridae, the elephantfishes and mormyrids, within the order Osteoglossiformes — the bonytongues, one of the oldest surviving lineages of teleost fishes.
The genus name Petrocephalus comes from the Greek petros, "rock" or "stone", and kephale, "head", a reference to the hard, bony head typical of these fish. The species epithet valentini is a Latinized genitive — "of Valentinus" or "of Valentin" — the standard construction for a name honoring a person, but the original description's dedication is not stated in the sources reviewed for this account, so who the name commemorates is not established here. The type series came from the Lékoli River system within Odzala National Park, the same general locality that produced the other four species named in the 2010 revision, though the specific holotype data for P. valentini is not available in the sources consulted.
Morphology
The original description places Petrocephalus valentini among a set of small, similarly built Petrocephalus sharing the Lékoli River system. The four other species named in the same 2010 revision range from about 3.5–5 in in standard length, and P. valentini can be expected to fall within a comparable range, though a specific maximum length for this species is not documented in the sources reviewed for this account. Like other members of its genus, it has the compact, laterally compressed body and blunt, rounded snout typical of Petrocephalus — quite unlike the elongated, trunk-like chin appendage, the schnauzenorgan, that characterizes the more familiar aquarium elephantnose, Gnathonemus petersii.
As in every mormyrid, an electric organ in the caudal peduncle generates a weak, pulse-type discharge, read by electroreceptors spread across the skin and used for orientation in dark or turbid water. Because several similarly built Petrocephalus species share the Lékoli system, the 2010 revision leaned on this discharge waveform, alongside fin-ray counts and pigmentation, to tell the species apart — a reminder that outward appearance alone is often not a reliable guide within this genus. The specific waveform parameters recorded for P. valentini are not available in the sources reviewed for this account.
Habitat
Petrocephalus valentini is known from the Lékoli River system within Odzala National Park, Republic of the Congo — the same middle Congo River basin locality that produced the other four Petrocephalus species described in the 2010 revision. Whether the species extends beyond this immediate area, as some of its Odzala congeners do into neighbouring drainages, is not established in the sources available for this account.
Published water-temperature and pH data specific to this species are not available. Like other Congo basin mormyrids from forest-stream habitat, it can be assumed to live in warm tropical water, but that is a general expectation for the region rather than a measured figure for this population.
Feeding
No dietary study specific to Petrocephalus valentini has been published. Other Petrocephalus species forage on benthic invertebrates — insect larvae, worms and small crustaceans — located in mud, sand and leaf litter using their electric sense, and this species is presumed to feed the same way, though that has not been directly documented. No aquarium feeding record exists for the species, since it has no established presence in the hobby.
Mating
No courtship or mate-recognition behavior has been described for Petrocephalus valentini. Across the Mormyridae, the electric organ discharge is known to carry species- and often sex-specific information and is thought to play a role in courtship and mate recognition, but how any individual species uses its discharge to pair up has been studied closely in only a handful of well-known mormyrids, and this is not one of them.
Breeding
No spawning has been recorded for Petrocephalus valentini, in captivity or in the wild. Breeding biology across the genus Petrocephalus, and the family Mormyridae more broadly, remains poorly documented, and this species is no exception — nothing about egg deposition, incubation or parental care has been published. The species is not known to be kept or bred in aquaria, so no captive spawning account exists to draw on.
In the aquarium
Petrocephalus valentini has no established presence in the aquarium trade and no documented aquarium-keeping history; it was described in 2010 from a national park research collection, not from trade specimens, and nothing in the literature suggests it has since reached hobbyist tanks. Any care notes offered here are extrapolated from mormyrids in general rather than drawn from direct experience with this fish.
Small mormyrids of this kind are generally kept over soft sand for probing, with dim lighting and ample cover, in stable water with minimal turbidity — the group is well known for sensitivity to poor water quality and to some medications, including many common ich and parasite treatments, so cautious dosing and gradual acclimation matter more than with most community fish. Live or frozen invertebrate foods offered after dark suit the natural foraging behavior of the genus better than daytime flake feeding. None of this substitutes for a documented care record specific to Petrocephalus valentini, which does not exist.
Conservation
Petrocephalus valentini has not been evaluated by the IUCN Red List. It was described relatively recently, in 2010, and — so far as the sources reviewed for this account show — is known only from its type locality in the Lékoli River system of Odzala National Park, Republic of the Congo.
No species-specific threats have been documented. As with other freshwater fishes restricted to Congo basin forest streams, habitat disturbance, deforestation and water-quality change in the wider region are the kind of general long-term pressure that could affect a narrow-range species like this one, though that is a general concern rather than a documented one for Petrocephalus valentini specifically. The type locality's position within a national park offers some incidental habitat protection.