Sailfin Tang
I have a 55 gallon tank with a Sailfin Tang, Naso, Yellow Tang, Foxface, and a Percula Clown. I keep my SG around 1.022. My PH runs around 8.2, Ammonia 0, nitrites 0, nitrates around 5ppm,temp at 77, and calcium at 400. I add Lugol's iodine once a week, Strontium 2x week, There is about 35 pounds of live rock with various mushrooms growing, and a couple of feather dusters that have came out over the last few days. 
I vary there diet with frozen brine shrimp plus, flake foods, organic grown romaine lettuce, and SERA Tablets ( the stick on the glass ones.)
Now that's the specifics on the tank and its inhabitants now on to the questions.
My Sailfin has appeared to change colors. From black and yellowish stripes to an almost beige or tan color where they used to be black. Is this normal? Also this morning I saw him rubbing his head on the substrate (which by the way is aragonite) and I am wondering the best course of action. i.e. fresh water dip, medicated flakes etc. I know you gonna ream me out for this, but I don't have a quarantine tank setup to isolate the Sailfin. But all be it I'll have one soon...Also any other suggestions would be appreciated. Thanks, Brian...
<<Hmmm, not so fast... the color changes you mention and the "scratching" behavior may well not be indicative of a parasitic or other diseased condition... They may be "natural"... I'd hold off on dipping, any other chemical manipulation till you actually see some physical manifestation on the fish itself.
One thing I would do that will help, and has little potential downside is add a cleaner shrimp... one of the species of the genus Lysmata. Bob Fenner>>