They can get up to 9ft. Not a specimen anyone could keep really. If it helps put it in perspective, my friend is an underwater welder. His buddy was diving near the keys and working on a pipe when a Goliath Grouper snuck up on him and swallowed him up to his shoulders. His dive buddy (they work in pairs) had to literally pound on the grouper's eye a few times and it spit his friend out. If the fish is big enough to almost swallow a 5'8" person, you probably shouldn't have it in your aquarium.
