Fish
Tigerfish
Hydrocynus · also called tigerfishes, goliath tigerfish
A tigerfish is a striped, muscular African river fish with a mouthful of interlocking daggers, built to run down other fish in open, fast water. The small ones are Africa’s most prized game fish. The big one — the goliath tigerfish of the Congo — reaches 50 kilograms, is feared as the “African piranha”, and has been filmed leaping clear of the water to snatch swallows out of the air.
Overview
Tigerfish are the genus Hydrocynus, about five species in the rivers and large lakes of sub-Saharan Africa — the Congo, Nile, Niger, Zambezi, Okavango, and more. They are characins, related to piranhas and tetras, and fast open-water pursuit predators of other fish, with a deep body, a forked tail, and reddish fins. Lost teeth regrow through life, sometimes the whole row at once.
The goliath
The goliath tigerfish of the Congo basin reaches 1.5 m and 50 kg, among the largest freshwater predatory fish anywhere. It can swallow prey a third of its length, has injured and reportedly killed people, and, like all tigerfish, has acute hearing — a chain of bones turning its swim bladder into an amplifier for detecting struggling prey in murky water.
Fish that catch birds
In 2014, scientists filmed African tigerfish at a South African dam leaping to seize barn swallows in active flight — the first firm evidence of a freshwater fish habitually taking birds on the wing.
Status
Most species are Least Concern, but the goliath tigerfish is Near Threatened and declining from overfishing (including fine nets taking juveniles), damming of the Congo, and catchment pollution, worsened by its slow growth. The smaller species face rising angling and subsistence pressure across the Zambezi, Okavango, Nile, and Niger.
Tigerfish: common questions
Is a tigerfish the same as a piranha?
They are relatives but not the same. Both belong to the large order Characiformes, the characins, which also includes tetras, and both are toothy predatory fish, so the tigerfish is often called the African piranha. The differences are size and lifestyle. Piranhas are South American, mostly under 40 centimetres, with a single row of triangular interlocking blades used to bite chunks out of prey, and many are as much scavengers and fin-nippers as hunters. Tigerfish are African, range up to 1.5 metres in the goliath, have longer conical fangs, and are fast open-water pursuit predators that chase down and swallow whole fish. A goliath tigerfish is closer in ecological role to a barracuda than to a piranha.
How dangerous is a tigerfish to people?
The small and medium tigerfish are not a serious danger, though an angler can get a nasty cut from the teeth of a thrashing fish being unhooked. The goliath tigerfish is a different matter. At 50 kilograms with fangs several centimetres long, it is large and powerful enough to injure a person, and there are credible reports from the Congo of goliath tigerfish biting swimmers and people wading or falling from boats, with at least one fatality attributed to the species. Attacks are rare, and the fish is not a habitual predator of people, but in goliath country the sensible advice is not to swim, wade, or dangle limbs where the fish are known to be.
Do tigerfish really jump out of the water to catch birds?
Yes, and it was documented properly for the first time in 2014. Researchers studying African tigerfish at Schroda Dam in South Africa observed and filmed the fish repeatedly launching themselves out of the water to grab barn swallows that were flying low over the surface, catching an estimated several birds per fish per day during the swallow migration. Fish taking birds from the surface, such as an arowana grabbing a resting bird from a branch, was already known, but a fish habitually intercepting birds in active flight had not been confirmed before, and it showed a level of speed, aim, and timing that surprised biologists.
What makes tigerfish such a famous sport fish?
For African anglers the tigerfish, especially the species of the Zambezi and Okavango, is the premier freshwater game fish because of how it fights. It hits a lure or bait with a fast, hard, slashing strike, is difficult to hook because its bony mouth resists the point, and once hooked it makes powerful runs and repeated jumps, often throwing the hook. It is also handsome, silver with dark horizontal stripes and orange-red fins. The goliath tigerfish adds sheer size and the remote, difficult setting of the Congo, which makes landing one a rare achievement among sport anglers.