HELP - Fish Illness

[TheReefGeek]

Tank parameters are perfect, im not going to list them all though. The foxface is eating a wide variety of foods, different types of macro algae, regular and veggy flake food, and my variety of frozen foods (marine diet, mysis, brine, etc, etc all blended together and frozen in 1 big block)

I am confident this is not from my tank, none of my other fish show any signs (YET, keep my fingers crossed) and this is a recent addition, so im pretty sure the foxface brought whatever this is, in with him.

I will do some research on black spot and maybe that is it.

Catching him will be a bugger.

Can I get more details on a fresh water dip? What is involved? Heat the water then bring the PH up? Anything else? Just leave him in there for 5 minutes? I have not had to do this before, thanks for the help.