You can isolate him, but unless you think he is really sick I do not know about just going ahead and medicating without some definite symptoms. You may make him resistant to that medication and there may be a time in the future when you really NEED it.
I would try to isolate him if you could for at least a week to 10 days (if you can) just to make sure, but watch and unless he develops a definite set of symptoms to work from I don't think I would try the medication. Unless you want to try something fairly safe like Pimafix. It is herbal and would not be something he would build up a resistance to. (Pimafix is for parasites, Melafix is for disease. They are both herbal type remedies and pretty much easy on the fish. You can use them for a week (one dose daily) before you do a water change. They are also one of the only types of medications that it is okay to use in conjunction with other things.
I hope that this has helped a little.
Rose
