What is wrong with this tang?

[linda lee]

Will try to get a picture tonight.

Large tang has what looks like rust across the top of its body (for about a week) and now the flesh is deteriorating from the top fin -- can see the bones underneath.

Any idea what this is and how to treat? Fish has lost some color but is swimming around fine, although obviously stressed, and is still eating.

 

[jmaneyapanda]

Might be fin rot, or other bacterial agent. Please get a pic up. You will almost absolutely have to pull him for treatment, as you dont want to put antibiotics into the display.