Piranhas have never had the best of reputations. Read the word 'piranha' and the image of a swarm of blood-thirsty fishes with teeth like razor blades pop into mind. 

And it's also no thanks to movies like Piranha 3D, in which a pack of genetically-mutated piranhas escape a science lab and feast on unsuspecting swimmers. 

Devouring humans in full 3D glory.

Devouring humans in full 3D glory.

But are these freshwater fish the vicious water monsters they’re made out to be?

Not exactly.

Thanks, Teddy Roosevelt

The whole idea of the savage man-eating piranha started with author and one-time President of the United States, Theodore Roosevelt, when he wrote about them in his 1914 book, Through the Brazilian Wilderness.

Roosevelt traveled to South America in 1913 after his presidency, where he encountered several different species of piranhas. Here's what he wrote about them in his book:

"They are the most ferocious fish in the world. Even the most formidable fish, the sharks or the barracudas, usually attack things smaller than themselves. But the piranhas habitually attack things much larger than themselves. They will snap a finger off a hand incautiously trailed in the water; they mutilate swimmers—in every river town in Paraguay there are men who have been thus mutilated; they will rend and devour alive any wounded man or beast; for blood in the water excites them to madness."

Roosevelt went on to recount watching a pack of piranhas devouring an entire cow. According to Mental Floss, the locals wanted to put on a show for Roosevelt. Days before he was to arrive, they used nets to block off a section of the Amazon river. Then, they caught piranhas from other parts of the river and tossed them into this makeshift aquarium. For days, they kept the fishes unfed. When Roosevelt finally rolled into town, the locals chucked a live cow into the water.

Kinda reminds you of this "Jurassic World" scene, doesn't it

Kinda reminds you of this "Jurassic World" scene, doesn't it

We can all guess what happened next. The starving piranhas wasted no time in sinking their teeth into their meal. Within minutes, the cow’s skeleton was all that was left. To Roosevelt’s eye, the water churning up and turning red, along with the screams of the poor cow, likely made it seemed like the piranhas were the perfect killing machine.

A fish that can eat a cow makes for a great story. Given that Roosevelt's book was also widely read, it’s easy to see how the piranha’s supervillain image soon spread. 

The major exaggeration

However, recent research on piranhas suggest that they are actually far from dangerous. In fact, they make for pretty harmless swimming companions too! 

Wildlife writer Richard Conniff was one of those keen to debunk the myth of the monstrous piranhas, and he went swimming with them in numerous occasions - by standing in the Amazon river fishing for them while they swam around him, to getting up close and personal with the supposedly deadly fish in a Dallas Aquarium in front of gawking onlookers.

He even once tried to prove the whole "piranhas stripping a man or cow to bones in mere minutes" theory by feeding chickens to a swarm of piranhas to see how long it would take them to devour the whole thing. It took an entire afternoon, and even at the end of the day, the chickens were mostly intact.

When Conniff spoke with fishermen who lived and worked alongside the notorious fishes, he found that those who lived nearby agreed that the reputation of the piranhas had been blown way out of proportion. Those who live there found that the piranhas are more scavengers than hunters.

Piranhas will stake out an area where fishermen go to gut their fishes, and scavenge on the cast-off leftovers as the fishermen toss them overboard. They are also known to lurk under the nesting grounds of birds, waiting for bird babies to unfortunately fall in the water. When humans get bit, they’re usually of living people falling into the water by accident while the piranhas are already in the midst of swarming a dead or scavenged kill.

Some are even vegetarians

Some species of piranhas are omnivorous, eating more seeds than meat. And some with the unflattering nickname given by the locals of "vegetarian piranhas" live solely on the diet of riverweeds.

They even have human-like teeth with flat edges that are used for crushing seeds and nuts.



Now that you know the piranhas' fearsome reputation is largely undeserved, we hope that tales of man-eating fishes remain only as scary tales to tell around a chalet BBQ pit instead of as facts.