First of all, I've raised Pacus but did the inevitable - passed them along as they grew up (14 inches or so)
Largest I've seen was a monster 3 1/2 to 4 footer (had about 2 to 2 1/2 foot tall body) in a small store in Newton, Mass (The store is probably gone now) Anybody remember him? No, I am not kidding, or exaggerating. He was a total monster. (This was about 15 years ago)
Third - That means... all of you people with "2 foot high" tanks... Come on. 2 feet is hardly enough space for a Pacu to enjoy swimming up/down as they enjoy doing.
And as for those who state they are mainly vegetarian. They LOVE their meat. Even in nature.
For those who have read the MYTHS thread, I believe I've just taken care of a few myths about Pacus lol.