Petrocephalus is a genus of African elephantfish in the family Mormyridae, distributed widely across sub-Saharan Africa — the atlas's 48 species are drawn from the Democratic Republic of the Congo, Angola, the Republic of the Congo, Cameroon, the Central African Republic, Côte d'Ivoire, Guinea and Gabon, spanning both Congo basin rivers and separate West African drainages. Sizes run 2–8 in. Like other mormyrids, Petrocephalus fish generate a weak electric field from a specialized organ near the tail, used to navigate and locate food in dark or turbid water and to communicate with other fish through the signal's pattern; the genus is distinguished from close relatives such as Gnathonemus mainly by its comparatively short, unelongated snout rather than a trunk-like chin.
Elephantfish are a specialist rather than mainstream aquarium interest: Petrocephalus species — sold in the trade under names like baby whale (P. bovei) and Churchill (P. catostoma) — are kept by hobbyists drawn to their unusual sensory biology, but they need soft, stable water, subdued lighting, and tankmates that won't out-compete a shy, largely nocturnal fish for food. Petrocephalus also stands out among mormyrids for having the largest brain-to-body-mass ratio of any fish genus, a fact tied directly to the processing demands of its electrosensory system. Conservation-wise the genus reads as low concern on current data — the atlas tally is mostly Least Concern (18) or Not Evaluated (23), with a scatter of Data Deficient records and just one Near Threatened species — though, as with many African riverine genera, that likely understates how little some populations have been surveyed.