One of my all time favorite fish. Never heard it referred to as a sailfin, but I can see why that would happen. Vibrant coior, very active, great algae cleaner. A bit on the aggressive side, but MOST tangs are anyway. One of the few that is basically NEVER collected with cyanide, since they are endemic to the Red Sea, and are almost always healthy. Like most tangs, it can be an ich magnet, but generally, good quarantine procedures take care of that problem anyway.
Like many tangs, they can develop HLLE pretty quickly in poor water conditions or from poor nutrition. It never completely heals, but is reversible. (usually some scarring remains)
Here are a couple of "stolen" pix. One from our own "Alice Curiouser"...her purple tang, Moshe...as posted over at Reef-Vision:
And one from our resident Mermaid, the lovely Miss Mary:
