yellow eyed cole tang question

anyone know of a disease the yellow eye, is prone to carry?
i just purchased my second one, after the first died, and am going to QT him for about a month.
my other one developed blotches over it's body, and died shortly thereafter, taking about 5 fish with it.
i love the fish, but am paranoid to put him in my main tank.
can you guys fill me in, if you know anything?

 

If you are going to Q/T the fish then treat the fish with a simple antibiotic to clear up any problems that may be from a disseas from a holding system do a 7 day course and then a with a little 1/2 dose copper treatment as copper can kill them from accumulating in their livers and such . It may the collection methods used ? Lots still employ cyanide poison and there is also a oils from a plant that will knock them out like a near death tcomma in some areas of the world that name escapes me know of the root used ?

 

this guy appears to be healthy. i just don't want to take any chances, like i did with the last one.
want to make real sure he's healthy, before adding to the main tank.

 

they used the root on man vs. wild name escapes me though, if it is too strong it can easily kill the fish