angelfish tend to do best when kept in groups of 5 or more of their own species. This is certainly one option that will guarantee that your angelfish do not have trouble with aggressive tank mates. Even if you do plan to keep primarily angelfish, adding a few corydoras catfish or other peaceful bottom feeders would not be a bad idea. If you do plan to keep other fish in the tank with your angelfish, however, you are unlikely to encounter problems with livebearers or peaceful tetras. Even small cichlids like rams, Krib’s cichlids and keyholes can cohabitate peacefully with angelfish.