Taxonomy & naming
Petrocephalus keatingii was described by the Belgian-British ichthyologist George Albert Boulenger in 1901, with a type locality at Fashoda (present-day Kodok) on the White Nile River in Sudan. It is placed in the family Mormyridae within Osteoglossiformes, the bonytongue fishes, one of the oldest surviving lineages of teleosts. No subgenus placement or synonymy is documented for this species in the sources consulted for this account.
Genus Petrocephalus, the churchills, comprises several dozen small African mormyrids with a rounded, blunt head and a short snout, distinguished from related genera such as Gnathonemus and Campylomormyrus by the absence of an elongated, trunk-like chin organ. Many species in the genus were only resolved through taxonomic revisions in the 2000s and 2010s that leaned heavily on electric organ discharge waveforms alongside morphology, since the fish themselves can look very similar across species.
Morphology
Petrocephalus keatingii reaches about 4.5 in in total length, a modest size within the genus. The body is compact, with the depth going roughly three times into the total length and the head length going four to four-and-a-third times into it. The head itself is rounded and as long as it is deep, with a very short snout that projects slightly beyond a small mouth set low on the head — the blunt-faced profile typical of Petrocephalus and quite different from the elongated snouts of trunk-nosed mormyrids.
As in every mormyrid, an electric organ near the base of the tail generates a weak, pulsed electric field, read through electroreceptors spread across the skin and used to navigate and sense surroundings in turbid or dark water. No electric organ discharge waveform has been published specifically for P. keatingii, but related Petrocephalus species from the Upper Volta system produce short, triphasic pulses on the order of 144 to 663 microseconds, and differences in amplitude, duration and dominant frequency between such waveforms are often the more reliable way to separate species in this genus than external appearance alone.
Habitat
Petrocephalus keatingii is known only from Sudan, recorded from the White Nile River system between the Sobat confluence and Khartoum. It occupies freshwater, demersal habitat in a subtropical river setting, with reported water temperatures spanning roughly 20 to 30 degrees Celsius across that range. No pH or hardness data specific to this species is documented in the sources consulted.
Feeding
Published diet information for Petrocephalus keatingii is limited to a general trophic-level estimate placing the species at an intermediate position in the food chain; specific prey items have not been documented. Like other mormyrids, it almost certainly forages for small invertebrates hidden in bottom sediment, locating them by electrolocation rather than sight, but that habit has not been confirmed directly for this species in the available literature.
Mating
No courtship or mating behavior has been documented for Petrocephalus keatingii. Across Mormyridae more broadly, the electric organ discharge is thought to carry a role in mate recognition and courtship signalling in addition to navigation, but nothing published for this species ties that general pattern to its own reproductive behavior.
Breeding
Breeding has not been recorded for Petrocephalus keatingii, either in the wild or in captivity. No spawning account, egg description, or parental-care observation exists for this species in the sources consulted, and none should be assumed from what is known of other Petrocephalus species.
In the aquarium
Petrocephalus keatingii has essentially no documented history in the aquarium hobby. An aquarist encountering it would be working from general mormyrid husbandry rather than any experience specific to this species: soft sand substrate for probing, dim lighting, ample cover, and stable, clean water, since mormyrids as a group are known to be sensitive to poor water quality and to many common aquarium medications. Live and frozen invertebrate foods such as bloodworm and brine shrimp are the standard offering for mormyrids that will not reliably take flake or pellet food.
FishBase rates the species' resilience as high, with a population doubling time under 15 months, and gives it a low vulnerability-to-fishing score — figures that describe its biology in the wild rather than any track record in captivity, which for this species does not exist.
Conservation
The IUCN Red List assessed Petrocephalus keatingii as Data Deficient in 2009. No population trend, abundance estimate, or named threat has been published for the species since that assessment. Given how narrow its documented range is — the White Nile between the Sobat confluence and Khartoum — an updated assessment would depend on fresh distribution and population survey data from Sudan.