Orange Shoulder tang; disease, or natural change?

[michika]

This afternoon I noticed that the face on my orange shoulder tang has darkened, just above the eye. The tang was completely bright yellow on June 12th, 3 days ago. There are no abrasions, the fish hasn't been fighting or having problems with it's mates. So I've come to two possible conclusions; its a disease/illness, or its already starting to change to its adult form. The fish is just a tad bigger then an inch from mouth to tail.

These are the best photos I could snap, and of course the tang would only hang out in the cave once the camera came out. If you look closely you can see the darkening on its face.







Is my fish changing already? Does anyone know what the timeframe is for changes from the juvenile to adult forms? Or can someone direct me somewhere I can find one?