This is largely due to how the locals put on a show and exaggerated the brutality of piranhas. Since the locals knew that the famous Roosevelt was coming, they wanted to put on an incredible show for him. They decided to section of a part of the Amazon river and then caught and transferred piranhas to this part of the river. The fish were then left to starve until the day Roosevelt came by. On that day, they "appeased" the fish by sacrificing a live cow. The starving fish naturally shredded the cow causing the water to foam and turn red. Roosevelt naturally just a.s.sumed that they were born killing machines and described how they looked evil and ferocious.

Although piranhas have sharp teeth and most of them are carnivorous, they usually avoid larger animals. They instinctively act like fish and avoid larger fish by all means. Humans are only ever targeted if they are either dying or dead. The most that will happen is a few bites. Around 500 piranhas would still take 5 minutes to strip the flesh off a human. And the main reason piranhas move in packs is for safety and there have never been any reported cases of death by piranhas.

As already mentioned, not all piranhas are carnivorous and some are even vegetarians. Those mainly live off seaweed or riverweeds.

Interestingly enough, piranhas can create bark like noises.

Ps: They taste great