that is true, unless they are a breeding pair, there is apt to be aggression issues as they mature. that is why i suggested other fish and have a single angel as a centerpiece. this works well for my tank and i have room to add a few more fish due to the fact that all the angel's tankmates are small and will stay small.
i have an angel in with a variety of cichlids, including a peacock, but i think i just lucked out on a bunch of different rrrrreeeaaaalllllyyyy mellow fish, lol.