Concrete information yes, but justification for not trying to help a new comer not make his next post "why does my tang have white spots?" Thats when i get in trouble for pointing out the same old same old. Tangs are in general not as simple to keep IMO
as they are easily stressed if not housed and fed properly. Certainly a 1" tang in a 55 is good for a few years, but if you are successful, it will grow pretty fast. It was always hard to give up the fish when it got big, so the tanks got larger and larger at my house. Beware. I am not sure there is a cure for this or any going back.