what is this on back of tang??

[datsunfiveten]

hello i have a about an 7 month old tank. my second fish was this kole tang. i have 5 fish 2 clowns, malanarus wrasse, tang and a blue line rabbit fish. i am wondering what these lines are if you can see them in picture. they appear to be similar in color as the body but darker and have never noticed them before .tank is 125 gallon. tangs eyes look good. no clouding, i had a magnificent fox face die about 3 months ago. went from healthy to dead in about 48 hours. if that helps

 

[datsunfiveten]

No one knows or are the pictures not good enough?

 

[mattcoug]

I can't see anything wrong

 

[ThRoewer]

Looks like scratches to me in the pictures.

Does he behave as if something is bothering him?

 

[datsunfiveten]

Just those scratches. Not sure if they are something to be worried about.