The red belly pacu grows to a huge size of more than two feet, representing the very outer limit of how big a fish you can keep in a home aquarium. They strongly resemble their close relatives, the piranha. However, they eat mostly fruit and vegetables.
In the Wild
Scientists have looked at the stomach contents of wild red-bellied pacus. This helps us know what to feed then in captivity. In the wild, pacus eat a variety of foods. The main part of their diet consists of fruits, nuts and seeds. However, it will eat animal foods when the opportunity arises. For example, they will eat fish smaller than themselves, insects and animal-plankton. You should aim to imitate this diet in the captivity.
Juveniles
Many pet shops sell pacus when they are very small. When small, pacus act like many other community fish, and get along well with other species. Juvenile pacus will readily take fish flakes and other commercial fish food. Even at this stage, you should make an effort to include green foods in their diet. The easiest way to do this is with prepared foods formulated for vegetarian fish, like spirulina flakes or algae wafers.
Prepared foods
As an adult, pacu will rarely take flake food. However, they will accept other prepared food with more substance to them. Floating pellets and freeze-dried food have nearly the same level of convenience as flake foods. Try to get preparations that contain vegetable matter, like algae pellets and wafers. Floating foods work better than sinking ones. Pet shops often have a variety of foods available.
Vegetables and Live Food
You can (and should) also feed your pacu many of the same fruits and vegetables you eat. Pacus love peas, grapes, broccoli and banana. Break food into small enough pieces for your fish. Raw vegetables and vegetable-rich prepared food should comprise the bulk of their diet. However, pacus also enjoy the occasional live treat like crickets or feeder shrimp to mimic their diet in the wild.
