Tangs and large swimming fish are usually good. Never any puffer fish or triggers, and moniter with harlequin tusks (im keeping a close eye on mine) Wrasse are good suggestions, and also bottom dwelling sharks and smaller types of eels, like chainlinks and snowflake eels, cuz bigger ones can still eat lions believe it or not. Its tough having a compatible environment for a lionfish, and u need a large tank as well, but i believe they are worht it.