Taxonomy & naming
Petrocephalus sullivani was described in 2004 by Sébastien Lavoué, Carl D. Hopkins and Antoine Kamdem Toham. It belongs to the family Mormyridae, the elephantfishes and mormyrids, within Osteoglossiformes, the bonytongues — a deep-time lineage of freshwater teleosts found today in Africa, South America, Southeast Asia and Australasia. Petrocephalus is one of the larger genera in the family, and many of its species look very similar externally; researchers working on the genus in the early 2000s, including Hopkins and his collaborators, increasingly relied on the waveform of the electric organ discharge alongside fin-ray counts and body proportions to tell close relatives apart, a method used throughout the period's Petrocephalus revisions. The Catalog of Fishes lists Petrocephalus sullivani as a valid species.
The holotype, exact type locality, and full comparative data given in the original 2004 description are not established in the sources consulted for this account. Prefer the original paper or Catalog of Fishes for those specifics rather than treating their absence here as evidence they were never recorded.
Morphology
No species-specific size or meristic data for Petrocephalus sullivani were available in the sources consulted for this account. Like other members of its genus, it can be expected to share the general Petrocephalus body plan: a laterally compressed, moderately deep body, a short and blunt rounded snout, and a small, underslung mouth set low on the head — a shape quite different from the long, trunk-like schnauzenorgan carried by the better-known aquarium elephantnose, Gnathonemus petersii. Described Petrocephalus species range roughly from about 2–6 in in standard length, but that figure is a genus-wide range, not a measurement of this species.
As in every mormyrid, Petrocephalus sullivani carries a weak electric organ in the caudal peduncle that produces a species-specific, pulse-type electric organ discharge, read through electroreceptors spread across the skin. Mormyrids also carry one of the largest brain-to-body-mass ratios of any vertebrate group, with an enlarged cerebellum devoted to processing this constant electrosensory stream — a trait that has made the family a long-running subject of neuroethology research, including work by co-describer Carl D. Hopkins.
Habitat
The type locality and confirmed geographic range of Petrocephalus sullivani are not established in the sources consulted for this account. No country, drainage, or habitat description specific to this species could be verified here, and none should be assumed from its congeners.
More broadly, Petrocephalus species occupy African fresh water — rivers, forest streams and floodplain habitats — where slow currents, standing vegetation and low visibility favour electrolocation over eyesight. Whether Petrocephalus sullivani fits this general pattern, or occupies some more particular habitat, is not documented in the literature available here.
Feeding
Presumed benthic invertivore, like other Petrocephalus, using electrolocation to find aquatic insect larvae, worms and small crustaceans hidden in mud and sediment — though no dietary study specific to Petrocephalus sullivani has been published, and nothing about its diet in captivity exists, since the species has no history in the aquarium trade.
Mating
No courtship or mate-recognition behaviour has been described for Petrocephalus sullivani specifically. Across Mormyridae generally, the electric organ discharge is thought to carry species- and sex-specific information used in mate recognition and courtship alongside its roles in navigation and prey detection, but this general pattern has not been confirmed for this species, and its own discharge waveform was not available in the sources consulted for this account.
Breeding
Unrecorded; no captive or wild spawning account is published for this species. Breeding biology across Petrocephalus and Mormyridae more broadly remains poorly understood even for far better-studied species, and Petrocephalus sullivani, with no aquarium history and no field study of its reproduction, is a clear case of that gap rather than an exception to it.
In the aquarium
Petrocephalus sullivani has no documented presence in the aquarium trade and no published husbandry record. Anything offered here is drawn from general mormyrid care rather than direct experience with this species, and should be read as a reference framework rather than an account of how this fish has actually been kept.
Small Petrocephalus of this kind are generally housed over soft sand for probing, with dim lighting and ample cover such as driftwood, pipes or dense planting, in stable, clean water with minimal turbidity. Mormyrids as a group are notably sensitive to poor water quality and to some common medications, so cautious acclimation and conservative dosing matter more with this family than with most community fish, and live or frozen invertebrate foods offered after dark suit their natural foraging rhythm far better than daytime flake feeding.
Conservation
Petrocephalus sullivani has not been evaluated by the IUCN Red List and is treated here as Not Evaluated. No population estimate, range map or threat assessment specific to this species was found in the sources consulted for this account.
Small-range Central and West African mormyrids described in the early 2000s are frequently under-assessed simply because so few field surveys have targeted them since their original description; that gap in the record should not be read as evidence of either safety or risk for this species.