Steve
Thanks for your answer. Good to be connected. As I suspected you got a alpha male.
Bojan
Beautiful tank. Good size for regal. You should make sure the regal eats well before you put it in the tank, or even consider taking out the tangs temporarily when you add the regal. The hippo and yellow tangs are as you know, pigs.
Andrew
Most regals IMO/IME are extremely shy and sensitive. My toddler runs past the tank few times a day and that always freaks her out. In the beginning she shut down for a long time. Lately she recovers quickly. As long as there isnt constant harrassment/movement, you should be fine.