Piranhas in the wild live only in South America, primarily in the Amazon River and other coastal rivers of northeastern Brazil. They require warm water to survive and do not eat when the water temperature is less than 54 degrees Fahrenheit.
Piranhas tend to live in rivers that empty into the ocean, such as the Amazon, Guyana and Essequibo Rivers, so they can take advantage of a natural phenomenon called pororoca. When pororoca occurs, ocean tides sweep into coastal rivers, often dragging animals into the river. The piranhas then feast on these animals. Piranhas live in schools of about 30 fish and work together to attack potential prey or scavenge for meals in unison.