I have had several of these in my life, including 5 of them that I own right now. They are VORACIOUS gulp eaters, and will eat until they literally cannot eat anymore, regardless of how recently they fed. Now, that being said, I will once again give my standard piece of info on tank size/fish size ratios: tank size limits fish size- PERIOD. A large fish species, if purchased small, will remain small in the environment in which he is placed. They will not grow larger than conditions can support them at.
And now, I wait for the inevitable flood of flaming over that last point...