I have a 5 1/2 inch Red Sea Regal for a while. I have had a few in my life. I think the trick is to let the Retailer QT your fish before you take him home. I bought my current one from a huge retailer that had about 6-7 specimens in a larger pool tank with other fish... He was there for 3-4 weeks and was treated and QT. When I observed him in this pool tank, all the Regal Specimens were eating aggressively a mixture of foods.... I didn't bother putting him through my QT... I had him hike and acclimated into my tanks water within 2 hours of leaving The retailer. Salinity was very close from retailers tank to my tank..... I had him eating, picking after acclimation with 24 hours. And fully eating all foods within 3-5 days.... After 2 weeks he became an animal with eating... Super aggressively attacking food... Mine devours Reef Frenzy, and will eat as much as I feed him. When he see's me, he rushes up to tank. I also hand feed him Medium Size Pellets. He gets his frozen and about 10 pellets twice a day. Other regals I have tried never lasted. I tried one last year, it wasn't eating at store.... Was a smaller specimen from Indian Ocean grey face. Only thing I saw him pick at was clams on half shell. He died about 8-10 days after intro.....
Here is my big guy!!! He’s the king of my tank!!!