It will take time and leaving the room the fish is in alone. If it is in a high traffic area, you can try to put some carboard around the tank for a few hours to let the fish get comfortable in the tank.I did put noir on a rock with rubber band and noir on a clip but I dont see him going for it
I forgot to ask earlier, but do you have pipe fitting in the tank, larger than the tang for it to hide?
Also, I just realized that it looks like you have sand in the tank. Is that correct? If so, the copper will bind to it and it will be heck trying to keep the copper at a therapeutic level.