If you wnat to place a grouper in your tank, make sure the other fish are venemous, or highly aggressive. I would recommend either a lion fish (volitan) or a member of the Foxface Family. SImply giving smaller fish a place to hide is not good enough when it comes to groupers. The species has a special adaptation in their jaw, so that when they open their jaw, it acts like a vaccuum. I've seen them scare off entire schools of Niger Triggerfish in Hawaii single-handedly.