Regal tang black fades
 

I have a regal tang that I purchased from LFS that looks healthy and is eating well. I have noticed that just after eating, his black stripe fades and turns grey...... Just for 10 minutes or so, then goes back to normal..... Is this normal? No ich or behavior changes. Just temporary loss of color

Excitement or timidness, this is normal when something is new to there environment as in food. You should see an Achilles being fed or spooked turn such a pale colour you think there dead.

My large Sailfin turns pitch black with a few gray spots when it has had enough of the cleaner wrasse or gets spooked.