I really don’t know about that either, but size doesn’t seem to hurt a tuna steak, although a grouper is from a different family of fish.
Haven’t had a good piece of grouper lately. I think I need to head for the coast a couple of days this spring.
For me the best tuna steak cooks up like beefsteak & needs a steak knife to cut it.
Or am I thinking of swordfish? Haven’t had either in a while.