Spot on purple tang

[FiberglassMonkey]

Hey I just got this tang from an established system a week ago. Looked real well when I got him. And noticing today he has a spot on him... Anyone know what it could be and treatment?

alt="">

alt="">

I have a few other tangs and don't see any real aggression...

All help is appreciated!
Thanks

 

[FiberglassMonkey]

Bump

 

[melev]

It should fade away. My purple gets a white patch on her side, around her mouth, etc... I think it rubs against something at night. Keep an eye on that area and see if it vanishes in the next 24 hours.