Fish
Goliath Tigerfish
Hydrocynus goliath · also called goliath tigerfish, giant tigerfish, mbenga
The goliath tigerfish is the Congo’s apex fish predator — a metre and a half long, up to 50 kilograms, with 32 conical teeth that slot together like a bear trap when the jaws close. It is one of the very few freshwater fish anywhere that will bite a person.
Overview
Goliath tigerfish live throughout the Congo River basin and Lake Tanganyika, in warm, well-oxygenated, often fast and turbid water. They are pure fish hunters, taking prey up to half their own length — including large catfish and smaller tigerfish — and occasionally snatching a bird from the surface.
The teeth
The fish has 32 replaceable, dagger-shaped teeth in a single row, all about the same size. When the mouth shuts, the upper and lower teeth interlock exactly, so the bite shears through a fish rather than just holding it. Prey too big to swallow is simply cut into pieces.
The hunt
It favours rough, murky river channels where prey has little warning, and it detects the low-frequency vibrations of a struggling or wounded fish through its lateral line before closing with a fast lunge.
Danger and sport
Large goliath tigerfish have injured swimmers and anglers in the Congo and Lake Tanganyika, though attacks are rare and the fish does not target people. It is also one of the hardest freshwater fish to land — a bony mouth, violent runs, and teeth that cut ordinary line — which draws specialist anglers to its remote rivers.
Status
The goliath tigerfish is Least Concern, widespread and generally common, with localised pressure from fishing and river-fragmenting dams.
Goliath Tigerfish: common questions
How dangerous is the goliath tigerfish to humans?
It is one of the very small number of freshwater fish that can seriously injure a person, but genuine attacks are uncommon. A large goliath tigerfish is a metre and a half of muscle with 32 interlocking teeth capable of shearing through flesh and bone, and there are credible accounts from the Congo River and Lake Tanganyika of the fish biting swimmers, taking chunks from anglers' hands, and severing fingers. Local fishermen in parts of the range genuinely fear it. That said, the fish lives mostly in remote, fast, difficult water where few people swim, it does not hunt humans, and most bites happen when a hooked or netted fish is handled carelessly. It is far less of a practical hazard than crocodiles or hippos in the same rivers.
Is the goliath tigerfish related to the piranha?
Only distantly — both belong to the large order Characiformes, which also includes tetras, but tigerfish are in an African family (Alestidae) and piranhas in a South American one (Serrasalmidae), and their similarities are a case of convergent evolution. Both are toothy predatory characins, but the details differ — a piranha has a short, deep body and a single row of triangular, blade-edged teeth built for taking bites out of larger animals and stripping carcasses, often while shoaling. The goliath tigerfish has a long, streamlined body and conical dagger teeth built to catch and cut whole fish in open pursuit, and it is more of a solitary hunter that grows many times larger than any piranha.
What and how does the goliath tigerfish hunt?
It is a fish specialist that will eat nearly anything it can overpower, including big catfish and smaller tigerfish. It favours fast, turbulent, sediment-laden stretches of river where visibility is poor and prey cannot see danger coming or use open water to flee. It is thought to rely heavily on its lateral line, sensing the low-frequency pressure waves made by a struggling, injured, or distressed fish — experiments on the smaller tigerfish species show they are tuned to exactly those frequencies — and then it accelerates into a strike. The interlocking teeth do the rest, shearing the prey so that even fish too large to swallow whole can be cut into pieces.
Why is it so hard to catch on a rod?
Anglers rate the goliath tigerfish among the toughest freshwater fish in the world to land, for several reasons at once. Its mouth is almost solid bone with very little soft tissue, so hooks struggle to find purchase and are easily thrown; the fish makes blistering runs in heavy current and repeatedly jumps and shakes its head; and its teeth will slice through ordinary line and light wire traces, so heavy tackle is essential. On top of the fish itself, its home waters — the rapids of the Congo and its tributaries — are remote, hazardous, and logistically hard to reach, which is part of the mystique for the specialists who travel to fish for it.