I also have a Koran Angel. Wonderful, hardy and a beautiful Angel. It grows quite large but the nice thing is that Korans are one of the slowest growers of the large Angels. It takes years before it outgrows your system.
Mine is housed together with a fully grown show size Yellow Tang, Lunar Wrasse, Six-Bar Wrasse, and a White-Striped Maroon Clown.
He's reasonably well behaved for a large Angel. From time to time he gets "bullied" by my 1.5" Maroon Clown. The little clown will actually chase him off out of his territory and he always complies

He has great respect for my Yellow Tang who is the undisputed boss of the tank.
To keep him happy, feed him a variety of foods. My fish eat Formula 1 flake, Formula 2 flake, Prime Reef flake, Pellets, Nori, fresh Spinnach and fresh saltwater fish/clams/shrimp form the supermarket which I blend and freeze into cubes.
Very personable. Eats right out of my hand. A great fish. Highly recommended!:thumbsup: