[Cindy, if you havent had ich in your tank, you wont likely get it unless you indroduce something new without being quarantined. I buy minced or chopped real garlic in a jar and use the juice from it, it is completely pure garlic juice where some of the extracts have other additives that I dont want to put in my tank.
Bolis, the nori is important for grazing and provides a lot of good nutrients. The regals require a whole lot more meatier food than other tangs though. I would suggest feeding mysis, formula 1 or 2, homemade mash(your own or get some from Nick), just about anything meaty they will go for, and I dont think Ive found anything that my hippos wont go for. Oh and skip the brine shrimp, it simply doesnt give them any nutrition. My regals wont allow a speck of algae to enter my tank, they like to keep those rocks super clean!]