Size matters as well. You cant put a juvie angel in with a large eel or grouper, so plan accordingly. I have an emp angel in my 220 I got as a juvenile- 3 to 3.5 inches. Over a year later hes grown all of 1 inch. I'm pretty sure a moray or grouper will outgrow any angel so plan on paying a considerable amount for an adult or plan on getting the others after your angel is pretty sizeable. Honestly, I wouldn't put a grouper in my 220. They get enormous, not just a foot long but Fat. they are messy, put a big strain on your system , and really need more space- but just my opinion.