Taxonomy & naming
Petrocephalus balteatus was described by the French naturalist Alphonse Trémeau de Rochebrune in 1885 as Mormyrus balteatus, one of many African mormyrid species he named from museum material in that period. It was later moved into Petrocephalus, a genus erected to hold the mormyrids with a short, blunt head rather than the elongated snout of relatives such as Mormyrus or Gnathonemus. FishBase currently treats Petrocephalus balteatus as a valid species, though some taxonomic authorities do not recognize it, and its status has not been revisited with modern material; the species should be read as taxonomically uncertain rather than settled.
The order Osteoglossiformes — the bonytongues — is an ancient, scattered lineage found today on four continents, and the family Mormyridae is its purely African, weakly electric branch. The genus name Petrocephalus is built from the Greek petros, "stone", and kephale, "head", describing the hard, blunt skull typical of the genus. The species epithet balteatus is Latin for "belted" or "girdled", from balteus, a belt or girdle — a common epithet for fish marked with a band or belt-like stripe across the body, though the original description that inspired the name has not been examined directly here.
Morphology
Petrocephalus is a genus of small, compact mormyrids with a short, rounded head and stubby snout, quite different from the trunk-like chin of Gnathonemus or the drawn-out face of Mormyrus. Like all mormyrids, Petrocephalus balteatus carries an electric organ near the base of the tail that produces a weak, pulse-type electric-organ discharge, and an unusually large cerebellum for a fish of its size, part of the enlarged brain that processes the constant stream of electrosensory information.
No species-specific length measurement for Petrocephalus balteatus was found in the sources consulted. The genus as a whole is uniformly small — most species run 3.9–7.9 in — and the well-studied congener Petrocephalus bane, a wide-ranging West African relative, reaches about 7.9 in standard length. That figure is a reasonable size ceiling to expect of P. balteatus, but it is a genus-level estimate, not a measurement of this species, and should be treated as such. Colour pattern and fine anatomical detail are likewise not well documented for this particular species.
Habitat
Petrocephalus balteatus is presumed native to Central Africa, most likely the Congo basin, based on the pattern of the other species Rochebrune described in the same period rather than on a precisely documented type locality. This places it, tentatively, among the region's river and floodplain mormyrids rather than in a specific named tributary.
Mormyrids as a group favour warm, soft, dim water — slow, turbid or tannin-stained river channels and flooded margins where visibility is poor and the electric sense does the work vision cannot. Petrocephalus species in general occupy both open water over sand or mud and vegetated margins within river and lake systems. No temperature or pH readings specific to P. balteatus were located, so the figures given here are drawn from the genus and family rather than measured for this species directly.
Feeding
Mormyrids are predominantly insectivorous, and Petrocephalus balteatus can be assumed to follow the family pattern: picking aquatic insect larvae and small invertebrates off the bottom and out of the water column, using its electric sense to locate prey it cannot see in dark or turbid water. Most mormyrids feed mainly after dark.
In captivity, the family is generally kept on sinking foods offered once lights are out — bloodworm, brine shrimp and other small frozen or live invertebrate foods — since diurnal, actively foraging tankmates will otherwise out-compete a fish adapted to nocturnal, electrolocation-guided hunting. No aquarium feeding record specific to this species was found.
Mating
Courtship in mormyrids runs partly through the electric organ discharge: each species produces a distinctive pulse pattern, and males and females are believed to use differences in that signal, along with its rate and timing, to recognize species and assess potential mates in water too dark or turbid for visual courtship to work well. This is a documented feature of the family in general; no courtship observations specific to Petrocephalus balteatus were located.
Wild mormyrids are largely seasonal spawners, with reproduction tied to the rains and to seasonal flooding of rivers and floodplains, but the details of pairing, spawning sites and egg deposition remain poorly known for most species, including this one. Data sparse.
Breeding
Petrocephalus balteatus has essentially no documented breeding record, in the aquarium or in the wild. Mormyrids as a family are seasonal, flood-triggered spawners, and while some species are thought to scatter eggs among vegetation with little or no parental care, the specifics are barely studied even for the better-known genera, and captive breeding of mormyrids of any kind is rare.
For this species specifically, there is nothing to report beyond the family pattern: breeding is poorly understood and has not been achieved, or at least not documented, in aquaria.
In the aquarium
Petrocephalus balteatus is not an established aquarium fish; it is a poorly documented species with no confirmed record of regular appearance in the trade, and this account should not be read as an endorsement of its availability. What follows draws on the care needs of Petrocephalus and Mormyridae in general, for anyone who does encounter it.
Mormyrids want soft, slightly acidic to neutral, dimly lit water with dense cover — plants, roots and caves — and do best given a sandy substrate they can probe. They are scaleless and notably sensitive to poor water quality and to many medications, so copper-based treatments in particular should be avoided and dosing done cautiously. Small Petrocephalus can sometimes be territorial or aggressive toward their own kind in close confinement, so tank size and cover matter more than headcount rules of thumb; a calm, dimly lit setup with peaceful, non-nipping tankmates suits the family better than a bright, busy community tank.
Conservation
Petrocephalus balteatus has not been assessed by the IUCN Red List; no species-specific conservation status was found. Many small Petrocephalus and other Mormyridae are similarly unassessed or listed as Data Deficient, reflecting how little targeted survey work these small, cryptic, electrically-sensing fish receive relative to their diversity.
In the absence of a dedicated assessment, the general pressures facing Central African river and floodplain fish — deforestation, sedimentation, damming and local overfishing — are the plausible long-term concerns for a Congo-basin mormyrid, but none of these has been documented specifically for this species, and its conservation status should be read as genuinely unknown rather than assumed safe.