The Red Belly Pacu is one of the largest freshwater species that can be kept in a home aquarium. Originating in the Amazon Basin of South America, this huge cousin of the Piranha grows quickly and can weigh over 50 pounds. As juveniles the Red Belly Pacu almost perfectly mimics a Red Belly Piranha for defense, but once they are large enough, not many fish species will ever bother them. They are a very hardy and long lived (20+ years) species. Red Belly Pacu require an aquarium of 500 gallons or more as they will grow large and will do it quickly; they also need to be able to turn around and are much happier in groups (and anything less than 500 gallons would unlikely support more than one specimen).