Here is a quote on them from an outside source.........
I would try keeping other less demanding crittesr for a while before tackling this guy.............
The Emperor Angelfish is considered moderately difficult to keep and is not recommended for novice marine aquarists. It should only be placed in mature and stable aquariums with ideal water conditions.
It is not advisable to keep an Emperor Angelfish in an aquarium smaller than 100 gallons / 375 litres. As the Emperor Angelfish grows bigger, you will probably need a 200 gallon / 750 litre aquarium if you want your fish to thrive. The aquarium should always include plenty of live rock for grazing when housing this species. It is also important to create a lot of suitable hiding spots, such as ledges and caves.
The Emperor Angel is considered reef compatible with caution. It will nip at stony corals, soft corals and clam mantles, but tends to leave somewhat noxious soft corals alone. If you want to keep stony corals, ideally go for variants with small polyps.
The Emperor Angel is a semi-aggressive species. It is highly territorial towards members of its own species and angelfish from other species. It is sometimes possible to house several angels together by picking fish of very different sizes and introduce the smallest specimens first.
