I had a girlfriend with a pacu who was still alive at age 30. You have to have a big freshwater tank, though. In the wild, they can reach lengths of 3 feet. Hers was about 20 inches and in 150 gallon tank. She eventually sold him to someone with a bigger tank. They are not for a beginner, either. Pacu are kin to the piranha and though they do not have the razor teeth, they have been known to bite. People who keep them in captivity (like my girlfriend) treat them with respect. Most pacu after being kept for a long time develop docile manners and actually become friendly toward their owners. According to an article in Wikipedia, a Chinese restaurant owner had one that rubbed him on his arm like a dog would.