Hydrocynus is the African tigerfish genus, a group of powerful predatory characins in the family Alestidae, the African branch of the broad tetra lineage. The atlas covers 5 species spanning an enormous size range, from roughly 10 in up to a reported 52.5 in in the largest species, found in river systems across West Africa, the Sahel, and the Nile basin, including Chad, Sudan, Egypt, Mali, Niger, Nigeria, Senegal, and Guinea. Tigerfish are built for pursuit predation: a torpedo-shaped body, large eyes, and a jaw lined with long, interlocking, dagger-like teeth that close outside the mouth when shut, letting them seize and hold fast-moving prey mid-strike.
The genus is best known outside ichthyology as a premier African sport fish. The largest species, the goliath tigerfish, has a reputation as one of freshwater's most formidable gamefish, capable of taking prey as large as smaller fish and, rarely, waterfowl, and is pursued by anglers on rivers such as those in the Congo basin for exactly that ferocity. Because of their size, predatory nature, and specialized dietary needs, Hydrocynus species are essentially absent from the home aquarium hobby; interest in the genus runs almost entirely through sport fishing and field biology rather than fishkeeping. All five species in the atlas are currently assessed as Least Concern, though local population pressure from fishing and habitat change is documented in parts of their range.
Tigerfish hunt by sight in open water, often in loose shoals that coordinate around baitfish schools, and several species undertake seasonal movements tied to river flow and flood-plain feeding opportunities, a pattern typical of large-river characins across tropical Africa.