My Emperor needs food

[revgeoff]

My 3 inch Pomacanthus imperator finally figured out that food goes in the mouth end. I was feeling embarrassed for the little guy, my tuka anthias were swiping his food as he "hunted" it.
Anyway, although I have been keeping marine fish for several years, this is my first large angel. I understand that the colour of the emperor angel, when it changes to its adult form, can be very pale. I am currently feeding a mixture of frozen food: spirulina brine, mysis, hikari mega marine angel mixure and sometimes large mysis or plankton. I soak this in selcon and garlic before feeding (oh, and of course green seaweed).
Can anyone who has kept this fish give me some suggestions on something to feed him/her so that he will be healthy and colourful when he becomes an adult?
Right now he is living in a 120gal that is slowly being converted to a reef tank (yes I know the risks of angels with corals...I am just stupidly hoping that if he grows up with them then he won't eat them when he is larger).
Thanks for any suggestions!