Yellow Tang-Red markings

[freebird]

Have a Yellow Tang that has developed red markings. The markings expanding from back tail, and seem to be getting bigger every day. Not sure what it is. any suggestions?

 

[freebird]

feeding mostly flake-some frozen, have had fish about 3 months

 

[beth]

That is a pretty bad diet for any fish, but especially for a tang.
Take a look at thefishfreak03's active thread here for dietary insight for your fish.

 

[daniel411]

Yellow Tangs are extremely active grazers, I always maintain either some croppings of algae from my refugium, or store bought leaflets for them to graze on.
I've had that red marking appear on my Yellow Tang a few times, its always gone away quickly though, I've heard its diet related, but can't positively say for certain.