you really cant have a angel or a tang ina 24 gallon, and really, adding the royal gamma is going to bring your bioload near to the limit. Tang need atleast a 75 gallon tank with lots of open water, even the small ones. Angels are similar but dont need as much swimming space, i think 30 gallons is a minimum but thats still small if you ask me. All angels are not totally reef safe and only a few oddities actually behave themselves from feasting on corals. If you want something interresting, buy a small reefsafe wrasse, that whont grom more than 4 inches. even then, wrasses can quarel with royal gamma