Rough purchase size 5-6cm
The Red Belly Pacu fish looks very similar and is sometimes sold to customers as the Red Belly Piranha. However, Red Belly Pacu only look like piranha as juveniles. The red belly pacu will grow rather quickly and may reach 12 - 24 inches (30 - 61 cm) if properly taken care of. Given their potential adult size you will need an enormous tank to keep one at home, at least 250 gallons (940 liters). You will also need an extremely efficient aquarium filter to filter the tank water.
The Red Belly Pacu will accept flake foods in the home aquarium but will need to be given pellets as they grow in size. It's probably best to keep them in tanks without live plants because they may eat your live plants.
Use caution when selecting tank mates for this fish. Even though they are herbivores, they may go after smaller fish in their tank. They can potentially be kept with arowanas and plecos.
The Red Bellied Pacu one of those fish that is best left to the advanced freshwater aquarist with a very large tank.