The largest piranha is the San Francisco piranha, which can be over 13 inches long and weigh up to 7 pounds. This piranha lives in the San Francisco River basin in Brazil, along with the red-bellied piranha, which can be 11 to 13 inches long and weigh 7 ¾ pounds.
Piranhas are known for their sharp teeth and aggressive nature. They typically feed off animals smaller than themselves, but if they are starving or provoked, a school of piranhas attacks larger animals together. The piranha's powerful jaws make it especially deadly. The black piranha can bite with a force more than 30 times its body weight, according to PawNation.