I really wouldn't recommend buying one of these fish unless you have at least a 2000 liter tank. They need a lot of room to swim, can get over 60 cm in length and are very skittish, especially if not in groups. If you scare them they can easily bust your tank. They are beautiful fish, but not exactly what I would say as a home aquarium compatible fish.
I got a pacu about two months ago and it is about ten times the size of when I got it. It will eat anything it can fit in its mouth. They say these fish won't eat meat, but mine do. I have my pacu in my aggressive tank and he does fine, but does not try to harm any of the smaller fish. Some of these fish do have problems with teeth, but it will usually heal soon. Do not be frightend when you see bumps coming out of the fish, because it's just the teath growing in. I would highly recommend this fish as a starter fish in a very large tank.
I love this fish. I keep 2 in a 400 L aquarium, with plans to move them to my indooor pond later on. They are rapidly growing fish, in just 4 months they have grown from 5 cm specimens to 22-25 cm monsters. Very hardy fish and good target fish for large breeding cichlids such as oscars and green terrors. They eat almost anything given to them and appreciate vegetable matter as well as the occasional frozen fish meat. I would like to stress however that you really need to consider the full size of these animals before buying.
I've had two Red Belly Pacu's for 6+ months in a 570 liter glass tank. I have 10 other fish of various sizes in the tank and they have not harmed the others. They are eating pellets, bloodworms, lettuces and dry catfood. They are very skittish and feed voraciously, but don't act aggressively unless positioning to feed.
I have a 570 liter with 4 red belly pacus and they eat like a bunch of dogs. I have had good luck with them, my largest one is probably 38 cm or so and my smallest is about 23 cm. There is a big black pacu who lives with them. I also have red terrors, a jack dempsey, 2 bullhead catfish, blood parrot cichlid, 2 midas cichlids, and 2 algae eaters. My tank is fun to watch at feeding time. They eat pellets, feeder fish, my plastic plants, small fruit, and just about anything edible that I put in the tank. I love the pacus, they are fast growers, easy to keep alive and pretty mean. I have noticed temperature is a big factor in keeping them healthy. I caught a 25 cm channel cat and dropped him in one day and they ripped him to shreds. So I wish everyone good luck with their tanks.
I have 2 Pacu's which I have had for only 4 months. When I got them they were the size of a quarter, Now they're the size of a small saucer and weigh over 500 grams each. They are currently in a 300 L tank, but soon I will need to find a home for them as they are already causing problems in this size of tank. Don't get me wrong, I love the fish and they provide a lot of enjoyment, but they are just getting too big and too quick.