Black spot/mark on Unicorn Tang

[BTCASTCS]

Hello,

My Unicorn Tang was fine about 1 hr ago and I noticed he started going at it with my Sailfin Tang. I have to mention I have a fox face and I am not sure if the wound is from a disease, the sailfin or the fox face... any one seen this before on any of their fish??

 

[griss]

@HumbleFish @leebca @Dr. Reef Any guidance?

 

[Dr. Reef]

If its black then it's likely battle wound. If it's red then it might be uronema but I am still leaning towards being battle wound

 

[BTCASTCS]

Thank you.
Update; he is still alive. He survived the 24 hours almost and the black spot is almost gone. Only a tiny black dot, where the wound was remained.