Why then do you have one?
From what I've seen there are two species from the Epinephelus genus that grow to ridiculous sizes:
Epinephelus lanceolatus- Common names= Bumblebee Grouper, Queensland Grouper or Giant Grouper (Unfortunately for these fish, they are more colorful than the itajara, with their bright yellow and jet black juvenile coloration that they lose as they mature).
Epinephelus itajara- Common names= Goliath Grouper (formerly known as the Jewfish)
Both of these species can grow to several hundred lbs.
What's your plan if the public aquariums can't take him?