Fish
Payara
Hydrolycus scomberoides · also called payara, vampire fish, sabre-tooth tetra
The payara, better known as the vampire fish, is a silver, torpedo-shaped predator of the Amazon and Orinoco, and it is named for the pair of dagger-like fangs that stick up out of its lower jaw. Those fangs can be six centimetres long — long enough that the fish’s skull has evolved sockets to receive them, so the payara does not stab itself every time it shuts its mouth.
Overview
Payara live in the fast-flowing water of the Amazon and Orinoco basins, concentrating below rapids, waterfalls, and river junctions where the current gathers prey. The species most people mean by the name commonly reaches 40–65 cm and can grow to a little over a metre and around 8 kg, with a streamlined, deeply forked, silvery body built for speed.
The fangs
The two lower canines grow 4–6 cm long in a big fish. The upper jaw carries matching sockets that the fang tips slide into when the mouth closes. The payara hunts by hitting a prey fish side-on at speed, driving the fangs through its body, then turning it to swallow head-first. Recorded prey includes piranhas — in these rivers, the famous piranha is itself food for something bigger.
A fish of the rapids
Payara hang in turbulent plunge pools and dart out to ambush fish swept past. They are a prized sport fish, striking hard and running fast, and notoriously hard to hook because a strike often glances off the bony mouth. Like other predatory fish, a payara regrows any fang it loses.
Status
The payara has not been assessed by the IUCN but is considered common and widespread. Despite the fangs and the name, there are no credible reports of it harming people; its teeth are made for gripping slippery fish, not for defence.
Payara: common questions
Why is the payara called a vampire fish?
Because of the two enormous fangs that jut up from its lower jaw. When the mouth is closed they project well outside it, giving the fish a fanged, predatory look that reminded people of a vampire's teeth. The name is purely about appearance and hunting style. Payara do not drink blood; they use the fangs to spear and hold other fish. In a large payara the fangs can be several centimetres long, and the upper jaw has a pair of grooves or sockets that receive the fang tips when the jaws shut, so the fish can close its mouth without driving its own teeth through the top of its head.
What does a payara eat, and how does it use its fangs?
The payara is an almost pure fish-eater. It hunts in and around fast water, ambushing prey fish that are up to about half its own body length. It hits the prey from the side at speed and drives its long lower fangs through the body, pinning the fish. It then manoeuvres the impaled prey around in its mouth until it can swallow it head-first. Smaller characins and other schooling fish make up much of the diet, and piranhas have been found in payara stomachs, so in these rivers the famous piranha is itself regular prey for something bigger.
How big do payara get?
It depends which fish people mean by the name. The species usually called payara in the aquarium and angling world, Hydrolycus scomberoides, commonly reaches 40 to 65 centimetres and can grow to a bit over a metre and around 8 kilograms. A closely related and larger species, Hydrolycus armatus, sometimes also called payara, grows heavier still. Either way these are substantial, muscular predators, and the largest specimens are strong enough to give an angler a serious fight in the current where they live.
Can you keep a payara in an aquarium?
Only in a very large one, and it is a demanding fish. Payara are active, fast-swimming predators that come from cool, highly oxygenated, fast-flowing water, and they grow large, so they need a tank of several thousand litres with strong filtration and current, which puts them beyond most home aquariums. They also need a diet of whole fish and can be nervous, injuring their fangs and snouts by dashing into the glass. For these reasons they are mainly a fish for public aquariums and a small number of specialist keepers rather than a practical pet.