:iagree:they grow up to a maximum of 24" yes. 12-24. If 240 is the best you can do, it's better than the lives most of them are destined to live, and better than the other options available. Considering they sell them at walmart and say they grow up to 8" at petsmart I think a 240G is going to be an awesome life for him.
If you keep smaller fish with him, jsut make sure you provide hiding places for them and keep him fed well.
I'm not aware of any healhy pacu that stops growing at 12"...:huh:
Fishbase lists its max size at about 42" (108 cm) and while I don't expect one to grow that large in an aquarium I would also not think of one stopping at 2 feet.