CTs are incredibly beautiful and interesting fish. They can go for a long time (sometimes years); then ivernight go postal and kill everything in the tank. They don't all do this, but watch him closely. Also, I'd avoid the very small ones ("baby" or "juvi"). They have a terrible survival rate. I'd get these two established first and wait a while before adding new fish. Avoid lions, IMO. These two triggers love to nip fins. You won't be able to add much; but I think fish to consider would be some of the larger wrasse..like a harlequin tusk. A tang, large angel, big maroon clown,or other larger, non-wussy fish should work too. IMO, you couldn't do better that an Australian harlequin tusk. Big, active, gorgeous,ignores almost all other fish. I have had excellent results keeping the tusk and CT together.