well depends on your experience level and how confident you are, but the OSFF is AMAZING and are coral eaters at first but are able to be weaned off coral with a little time a couple friends have one and im working with mine a QT tank now! also you can go with a pair of japanese swallow tails some people dont like them but i love them! if you like puffers you can do a mimic file fish which looks exactly like a valentini puffer. A Harlequin Tusk, Marine Betta just a few i could think of!