Discover The Largest Piranha Ever

Written by Emilio Brown
Published: January 1, 2022
Image Credit The Jungle Explorer/Shutterstock.com
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Piranhas are one of the most feared fish, not only for their bite but their ability to turn carcasses into skeletons. They live in river systems and freshwaters in South America and are a deadly predator for wounded animals swimming in the water. Size is not why piranhas are scary but the number of them that can be found together. Piranhas travel together in groups called shoals, and if they travel in a coordinated manner, it is called a school. Shoals have around 20 individuals but can have as much as 100. They live in shoals for protection but also to overwhelm prey.

Piranhas are usually small fish but have you ever wondered how large they are able to get? Large piranhas can be scary, considering the small ones are already so fierce. In this article, you will learn about the largest piranha species and other things about this biting fish. Sizes, location, and even bite forces vary depending on each species. Let’s go over some of the largest piranhas in the world and how big they can get. 

The Largest Piranha Ever

Largest Piranha - pygocentrus piraya (piraya piranha)
San Francisco piranhas (piraya piranhas) can reach pounds and 14 inches.

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It is estimated that there are around 30 to 60 species of piranha. The largest known species is the San Francisco piranha, also called the piraya piranha or black piranha. The San Francisco piranha (Pygocentrus piraya) average weight is around 5 to 8 lbs (2.2 to 3.6 kg). They regularly measure between 12 to 14 inches (30.4 to 35.5 cm). This species is the largest of any known extant piranha species and has a maximum length of 19.6 in. (50 cm).

San Francisco piranha lives in the Amazon basin and the Sao Francisco river in northeast Brazil. Some consider this species one of the most vibrant species of piranha. They have orange or yellow bellies with shiny silver bodies. Like other piranha species, they are omnivores. When kept in an area with limited food, they may become more aggressive and may attack whatever enters the water. This species is only endemic to South America waters. When kept as a pet, some may not know how large they can get. This is why some people may release them into non-native waters, which makes them invasive to different areas. 

Different Piranha Species And Size

Largest Piranha - Redeye Piranhas
Redeye piranhas can reach 13 inches in length.

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Piranha is the name used for a variety of fish that fall into this category. Piranhas are in the family of Serrasalmidae and are found in around 5 different genera. Here is each genera that encompasses pirahnhas:

  • Catoprion
  • Pristobrycon
  • Pygocentrus
  • Pygopristis
  • Serrasalmus 

It is estimated that there can be as much as 60 piranha species, or even less than 30. While that might sound like a large gap, remember that taxonomy debates are common across science and that many piranhas live deep in lightly inhabited areas across the Amazon basin.

Piranhas can only be found in South America in river and basin habitats in the wild. Different species exist in varying sizes. Another large species of piranha is the redeye piranha (Serrasalmus rhombeus), which is also often known as the black piranha. They grow to around 13 inches (33cm) on average and have a maximum weight of 6.6lbs (2.9kg). The largest redeye piranha ever recorded was 16.3 in (41.4 cm). Other names for this species include the redeye piranha, spotted piranha, yellow piranha, and white piranha.

Redeye piranhas also have the strongest bite record of any piranha and fish species fort their size. The bite force measured from the black piranha was at 320 newtons, which was about three times the force of an alligator of comparable size.

Smaller species also exist, and the smallest of all is the wimple piranha (Catoprion mento). This species will only grow up to 6 in (15.2 cm). Being so small, this species will not eat anything larger than it, and mostly survives on small fish, worms, and shrimp. This is a popular species to keep as a pet because of its small size.

Are Piranhas Dangerous to Humans

What do Piranhas Eat - Piraanha Teeth Close Up
Despite their appearance, piranhas are generally not dangerous to people.

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Piranhas might get a bad rep because of their sharp triangular teeth and the horror stories about this species. Usually, this fish is not dangerous and can even be shyer than other species of fish. People who live in areas with native species can swim with piranhas without being attacked. They would rather scavenge than hunt for their food. Wounded or dead animals make better meals than live humans.

In hot periods when food is scarce piranha bites may happen. These are usually nips and never dangerous attacks. One reason why piranhas have a bad reputation is because of former president and adventurer Teddy Roosevelt. He called these fish “the most ferocious fish in the world” and gave them the first bad impression. Some attacks from these fish do occur, but they are rarely deadly. The sound of a human swimming may sound like a fruit falling into the water, or a  wounded animal splashing. Fearing these fish is not necessary, as when we come across them in the wild, they fear us more than we fear them. 

The Megapiranha 

Giant piranhas are not only a thing seen in horror movies but once roamed the waters in South America like the species we have today. Megapiranhya is an extinct species that lived over 10 million years ago in the Late Miocene era. Research suggests they were able to reach 28 in (71 cm) and weighed around 22 lbs (10 kg). Compared to the largest species of piranha today, they can be seen as giants.


Teeth are the only fossil that has been discovered of this species. Comparing their size of teeth with piranhas of today, we can estimate how large they were. The Miocene period has some of the largest species of animal that look similar to the ones found in South America today, like the giant crocodile species. The piranhas that we see today have been around for about 1.8 million years, and it seems they may be around for much longer.

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