Are the Artemis (brine shrimp) live or frozen? If frozen I would suggest spirulina frozen brine as it has added nutrition. If live are you feeding freshly hatched or adult. If adult they need to be gut loaded (fed nutritious substances) prior to feeding.
I try to feed an assortment of frozen foods as well as live. I establish colonies of copepods and amphipods in my reefs. Then feed a blend of frozen: brine, Spirulina brine, and mysis.
my experience with angels is that they have specialized diets so I feed frozen foods designed specifically for angels. Many need sponge as a staple of their diet. Being that a Regal is considered a expert only angel I would strongly suggest a specialized diet for it.
A
I also feed garlic enriched nori daily.