Blue Tang white scratches/marks

[snailboy]

I have had my blue tang over 3yrs now and just recently she started gettng these marks on her. Does anyone know what may be causing them and how to fix them?
Tank Perimeters
PH 8.2
Nitrate 20
Amonia 0
Nitrite 0
Temperature 72
l

 

[gemmy]

What size is your tank? Do you have any means of QT'ing?

 

[mjm889]

did you add any new fish? could be stress, could be laterial line diease, how big is your tank and do put vitamins in with your food?

 

[btldreef]

That looks like the start of HLLE.
Take a look at these two threads:
https://forums.saltwaterfish.com/wiki/head-and-lateral-line-erosion
Look at Post #7 (specifically the Blue Hippo tang pics) and Post #8
https://forums.saltwaterfish.com/forum/thread/127010/diseased-fish-pictures#