Marine angelfish are typically aggressive especially to members of their own species. So how do you keep large angelfish together in the same aquarium?
The answer is location. By this I mean you need to keep large Angelfish that are from different regions of the world. If the Angelfish are not accustomed to seeing another Angelfish from another region it will not see it as a threat.
For example I keep a Maculosus Angelfish (Taiwan), Queen Angelfish(Caribbean), Passer Angelfish (Central America), and a Chrysurus Angelfish(South Africa) all in the same tank shown below in the video.
Do your research prior to buying your angelfish. It also helps to get them at the same time when they are young before the aggression has developed.