From what I know mandarins can not catch ich..im going to quote melevsreef on this one..
"These fish don't get Ich as they secrete an oily substance on their bodies. Their skin type and the oils secreted make them extremely sensitive to many medications. What may heal one species will more than likely kill a mandarin. So if your other fish develop ich, the mandarin is not to be put in to quarantine. Which is fortunate because it would starve to death if you did, assuming the medication didn't kill it first."
so no, i wouldnt qt him..or her..
They can and do get ich but are resiistive.There is no slime on the gill ,mouth or nose tissue as far as I know.
Do you have a source?very rarely, so problably it doesnt have ich..but treat it with cooper, and i promise you it will die.
Your best bet for him is going to be pricey.I just saw a couple of stops on my oscellaris and my basslet when one of my snails died and damaged the water quality...
right now everyone is doing fine, all spots are gonne, but know I know i got it in the tank and wanted to remove all the fish from the DT wait and put them back in when the life cycle passed...
But if I live the mandarin in there I think its like doing nothing.... if i take him out for 9 weeks... its killing him...