I think hes tryin to say he can get away with the grouper in a reef.
If so theres always a chance it will nip at soft corals and stuff,, annenoes,, possibly, But i would say the biggest fear facter of how big and gorky they are and knock over everything,, they are clumsy swimmers... But if everything is well placed,, then u can try it.... oh yea.. ull need a bigger tank once it reaches 5 in... they grow fast