In the wild, pacu fish are mainly vegetarians, eating algae, plants that grow on the river banks, fruits and nuts that drop into the river, and occasionally small fish and invertebrate animals. Pacu fish have a row of teeth that are adapted for grinding, cracking nuts and chewing. Pacu teeth are not sharp, like those of piranhas, but look like human teeth.
Captive pacu fish must have a similar diet to those living in the wild. You can give spinach, potatoes and other vegetables to a captive pacu, but avoid nuts, as they release oil after being crushed, turning the water greasy. Fresh food can increase the levels of contamination in the water, when not consumed immediately. Feed your pacu fish once a day and remove the food remains afterwards to avoid contamination. As an alternative, you can use processed plant-based foods and frozen fish foods, available at most specialised stores.
Pacu relates to nine genera of fish from the subfamily Serrasalminae, including Piaractus, Colossoma and Ossubtus. The red-bellied pacu (Colossoma brachypomum) and the black pacu (Colossoma macropomum), which is also called tambaqui and can weigh up to 66 lbs., are common species in the pet market. Ossubtus xinguense is an endangered species only found in the Xingu River, Brazil.
Pacu fish are found in some areas of the United States, including Florida, California, Georgia, Hawaii, Texas and Massachusetts. Species of the genera Colossoma were probably released in the wild after becoming too big for their fish tanks. As an invasive species, pacu fish pose a threat to native North American fish, as they compete for food.