Brienomyrus is a genus of African elephantfishes in family Mormyridae, part of the weakly electric osteoglossomorph lineage that also includes the true elephantnose fishes. Its atlas species span West and Central Africa, with records from Cameroon, the Democratic Republic of the Congo, Gambia, Guinea, and Sierra Leone, tracking the rivers and floodplain systems typical of mormyrid diversity on the continent. Like their relatives, Brienomyrus species generate a weak electric field from a caudal organ, using it to navigate, find prey, and communicate in the murky, structure-rich water they favor, mostly after dark. The two atlas species, brachyistius and longianalis, run 6.5–8 in.
Brienomyrus brachyistius, traded as the "baby whale fish," is the more familiar of the pair to specialist keepers drawn to weakly electric fish, though mormyrids as a group have a reputation for being sensitive to water quality, slow to settle in, and reliant on live or frozen foods rather than flake - traits that keep them a niche interest rather than a community-tank staple. Brienomyrus longianalis has little to no established trade presence. Both species are currently assessed Least Concern, indicating that, unlike some narrowly distributed African mormyrids, this pair is not presently flagged as under significant conservation pressure.