I recently had a compatability issue (at least I think is was a compatibility issue). I had an adult Coral Beauty and a juvenile Koran Angel. For many months they were inseperable. Then the Coral Beauty suddenly died. (My water parameters tested fine and the Coral Beauty didn't have any marks or discoloration on it. In fact he ate great the night before. Any ways the Koran Angel suddenly became very aggressive to the other fish (chasing). I have removed him for now (put him in a hospital tank). My 1' long Convict goby became a target for him. Before I bought my Koran Angel I read about it first (to try to eliminate any compatibility issues before I deceided to buy it). Nothing I read indicated that this fish could be so aggressive. Is this behavior typical of Koran Angelfish or is this a unusual thing? I really like the colorful species.