Fish guy..do you have any pics of the fish?
Not sure why you would have put copper into the quarantine tank for what you are describing as it is almost always more dangerous to treat a fish with the incorrect medication than to leave the fish in the QT under observation.
As copper is very rough on fish and rarely (if ever) used for anything other than the treatment of ich, I would suggest you do a 100 % water change and add a hang on filter with some carbon in it to remove as much as possible. Ideally, if you have another tank, I would move the fish into that with new SW (that is the same temp & salinity as the current water you have him in).
Can you tell us more about this fish..., how long you have had him, his age if you know, what he is fed, behavior, and anything else you might see out of the ordinary?
It would also be helpful to post the size of your system & parameters.