Regals like most other tangs are delicate fish that are highly susceptible to ick. The chance of the fish getting this parasite increases as the fish is exposed to more and more stress factors (bully fish, small tanks, etc.) Personally I think you should be ok with the tang in your tang as long as you don't plan on adding any other large fish. Other will tell you no, and that it needs a bigger tank but this is just from experience. I've raised 2 quater sized hippos to almost 5 inches together in a 70 with a powder brown tang and a kole tang w/o problems. Keep an eye out on the tang to make sure he doesn't come down with anything and he should start eating in a short time. The ones I've had ate like horses. It's also a grazing fish so try some romaine, seaweed selects, or nori in your tank too. Good Luck! Let me know if you have any other questions.
