When they said Rock Angel they probably meant Rock Beauty. If so I would not buy it just because I think it is one of those fish better left in the ocean. Anyways here is some info on the Rock Beauty angelfish:
1st off it gets @12in (32cm) in a tank. They are hard to feed cause they are very picky eaters. You can only keep 1 per tank as with most angels. Sometimes they can be very territorial and aggressive and they also need great water condictions, but if you take care of your tank that part would be know problem. As for their color they look awesome the juvs are yellow with a black spot on them and the adults have a yellow head, belly and caudal fin and the rest is black....
As for lfs it stands for local fish store.
hope I helped