The piranha is a freshwater fish that lives primarily in South American bodies of water, including lakes, floodplains, and rivers. The fish is well-known for its predatory abilities.

Their name comes from the Tupi language, spoken by the largest indigenous group in Brazil. “Pirá” means fish, and “sainha” means tooth. White settlers in the 1800s merged the two words.


Piranhas are small fish that grow between five and fourteen or fifteen inches, or twelve and thirty-five cm. There have been claims of larger specimens reaching up to twenty-four inches, but these accounts are unconfirmed. Extinct species may have been even larger. Piranhas are easily recognized for their unique, sharp teeth. They have a single row on the top and bottom of their jaws which are tightly packed and interlocked. Piranhas are well known for their bite strength. They have one of the strongest bites in the fish world that can pose a danger to humans, as well as a variety of prey.

Piranha close up
While stories exist of piranhas measuring more than two feet, most individuals are between six and twelve inches.


These small, omnivorous fish are indigenous to the Amazon basin, the rivers of the Guianas, and the São Francisco river system. Today, scientists recognize between thirty-eight and thirty-nine different species of piranhas. Twenty-five of these are from the Amazon. It is possible for species to exist together, but most occur in single river systems.


The piranha’s diet primarily consists of other fish, but they are omnivorous and will also eat plant material (like algae and aquatic plants). The fish prefer eating small species of fish, mollusks, lizards, small rodents, and insects. They have also been known to eat carrion or the carcasses of already deceased animals. They are opportunistic feeders, meaning that they eat what they come across rather than seeking out a specific type of prey.


Pirhanas lay their eggs in pits and protect them until they hatch. Newborns feed on zooplankton and small plant matter before growing large enough to prey on fish, mollusks, and other prey common to adult piranha’s diets.

Group of Piranha
Group of Piranha

Reputation and Danger to Humans

Piranhas are famous for their predatory abilities, their bite strength, and their danger to human beings. But, all three of these features are typically exaggerated in popular media. While there are records of piranhas attacking humans, this normally only occurs in extremely stressed situations when food is scarce. It is also suggested that distressed or injured swimmers are more likely to attract a piranha attack, as are fishers who are bringing in a number of fish at a time.

Historically, piranha attacks have caused minimal damage. But, there are reports of serious injury and even death. For example, in 2011, an intoxicated man in Bolivia was attacked and killed by piranhas while swimming. Another tragic incident occurred in 2012 when a five-year-old girl was attacked by a shoal by a group of piranha. These attacks, and others, have only darkened the fish’s reputation in popular media.

Piranha teeth
Piranha used tightly packed, serrated teeth to nip at larger fish or grasp small fish.


In their natural habitats, piranhas are threatened by predators like larger fish, crocodiles, and even mammals, like jaguars. Piranhas are generally categorized as of “least concern” or “not evaluated” by the IUCN. This suggests that the fish is not in danger of extinction, nor is the population declining. But, like all the world’s marine species, the piranha is affected by climate change, habitat encroachment, and the deletion of food sources.

Facts about the Piranha

  • Sometimes, piranhas are kept as pets, but they are illegal in some countries, like the United States.
  • They are often considered a nuisance to fishermen.
  • Piranhas are famous for their predatory abilities.
  • They have one of the strongest bites among bony fish.
  • Piranhas do not grow to more than 15 inches long.


Are piranhas dangerous?

Yes, they can be dangerous. There are many different reports of piranhas biting swimmers’ and fishers’ hands and feet. There are also recorded instances in which human beings were more thoroughly injured or even killed by these omnivorous fish.

Can a piranha eat a human?

Neither a single piranha nor a school of piranhas could likely eat an entire human being. But people should be careful in the water where these fish live. They are known to bite and even kill human beings.

Will a piranha bite you?

Yes, a piranha may bite you if they feel agitated or in danger. They might also attack if food is scarce or if there are a number of other prey fish around.

Can you swim with piranhas?

Yes, it’s possible to swim with piranhas but not advisable, especially in the dry season when food may be scarce. They do not prefer to but will attack human beings if they feel stressed.

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