I found this out the hard way but i'll tell you this so that maybe the other people starting out in SW
know this before it happens.
If you have a 20 gal
or smaller tank i'm totally against
the idea of mixing maroon clownfish, as I introduced another one following instructions (smaller size, same species ect) they tore into each other and one of them died. I'm treating the other one with melafix right now and it looks ok for him but besides losing an expensive fish it was a pretty sweet fish to lose also.