Don’t stick your hand in that tank, it’s a piranha! AAAAAAAHHHHHHH! Just
kidding! Although he may try to nibble at your hand if you stick it in his mouth, the red-bellied pacu (Piaractus brachypomus) is just a relative of the piranha. They do look very similar, however, and both live in the Amazon. These have been favored in home aquariums for obvious reasons (look like piranha (soooo cool!) without the risk of mistaking your finger for a tasty hotdog). However, they can grow to giant size VERY quickly. Pacu will eat just about anything they can get their fins on, and suddenly, that cute little softball size fish is now bigger than your giant turkey plate!
Pacu are mainly herbivorous fish, but can also be considered opportunistic feeders (if it fits, I eat it!). Feeding your fish the correct diet will keep them from growing at too rapid a rate. If you can be talked into trying a different species of fish that won’t swell to mammoth proportions, I would highly recommend it. If you must have the scary predator-like tank, then make sure you have a tank large enough for them to grow into (120″ x 36″ x 36 (300cm x 90cm x 90cm) MINIMUM! We’re not kidding, these fish need LOTS of room). Feed them appropriately with a wide variety of fruits and veggies mixed into their normal fish pellets. It is recommended that you keep them away from other species, since as they grow, their tank mates might start to look like hors d’oeuvres. Make sure to do plenty of research before starting your pacu tank. This is NOT a fish for beginners! For more infomation, check out this article from Seriously Fish.