More than 20 species of pacu fish originate in the Amazon River in South America. The pacu is related to the piranha, but instead of sharp teeth the pacu has teeth that strongly resemble those of humans. Many novice pacu owners are not aware that the fish can grow quite large and can live 20 years or longer.
No matter how small your pacu is in the beginning, keep him in an aquarium that provides 2 gallons of water for every inch of a fully mature pacu. Since he can reach 2 feet or more in length and 60 pounds in weight, you will want to start out with a tank of at least 30 gallons. Equip the tank with a quality filter capable of cleaning such a large tank, or two filters if necessary. Remove and replace 15 percent of the tank water one time per week to aid in the removal of toxins.
Proper Temperature and Decor
The pacu is native to the warm waters of the Amazon River. Simulate this environment by installing an aquarium heater and thermometer. He needs water temperature to range between 76 and 82 degrees. In addition, the pacu likes to hide, so be certain to equip the tank with lots and lots of cover using common aquarium décor including plants. Your pacu will eat live plants, so unless you want to regularly redecorate the tank, opt for artificial plants.
A pacu is omnivorous, meaning he will eat almost anything. But he prefers a plant-based diet. Offer him commercially prepared omnivorous fish food in proper amounts. A good rule of thumb is to offer him only what he can eat within two minutes. In addition to fish food, offer him raw vegetables such as greens and potatoes for his nibbling pleasure, but don’t leave these foods in the tank for more than three hours or you’ll risk toxins from decay.
Since the pacu will eat almost anything, you can't let him share a tank with smaller fish. If your pacu becomes so large that you cannot afford to upgrade the aquarium, consider a man-made outdoor pond. You still need to maintain the proper temperature, feeding and cleanliness as if he were in an indoor aquarium. If you decide that you can no longer care for a pacu, do not release him into local waters. Doing so is not only illegal in some states but is ecologically unsound -- the pacu could endanger the native fish population. Instead, put him up for adoption by contacting pet stores or public aquariums.