ID fish disease on TANG

[Nathan Fx]

Hi,

I got this guy for a week now, just notice this little spot on my tomini tang. He's really active and eat like a pig. This spot pop during the night, he was fine yesterday. I have a fish in the quarantine so I cant transfer him and I dont want to stress him out.

I just order some vitamin C to boost his immune system.
Can someone ID ?

Inside like relief.

thank you ;Yuck

 

[Old Fritz]

Do you have anything in the tank that is aggressive or anything that could sting?

 

[Nathan Fx]

Do you have anything in the tank that is aggressive or anything that could sting?

Not really, my Ellegance coral is the most aggressive coral I have. no anemone.

ty