Tangs has hole in head?

[jarrett shark]

I just noticed today that my small hippo and salfin tang have holes in there head?
What is it?
how do I treat it?
My hippois still very aggresive but salfin I noticed today not as aggresive.
What I mean by aggressive is my fish all folow me back and forth like they are hungry all the time. the salfin still eating but not as much. He only has one small hole and hippo has 3 small holes/

 

[Chris27]

Clean water and a vitamin enriched diet - all you can really do. Keep on top of them, and visually inspect them daily for signs of a secondary fungal or bacterial infection.

 

[boilermaker1]

I just got my hippo turned around and its healed back up. Lots of selcon and vitachem soaked food, lots of seaweed sheets and keep the water clean. It took about 6 months to clear up. He's still got a scar, its all healed over.