I have to say he seems pretty far gone, however, if you are willing, then you can try.
A rubbermaid is a good idea, and use egg crate for the cover. You don't want the fish in complete darkness, as sick fish are more likely to pass in darkness than not.
You will need to prepare a large amt of freshly well mixed salt water. Use the water in your display for your QT, but then replace the new salt water in the display. Cover the bottom of the rubbermaid with a very small layer of live sand from your display. This should just be enough to have a bit of sand, but not a thick layer.
Keep the water movement in the QT going throughout the system, and surface of the top should be rippling. If you can get a small pump that will shoot water up from the bottom of the rubbermaid to the surface that would be best. But don't make circulation so strong the fish is being banged about.
Be sure to add either fake rocks or PVC in for the fish.
At this point, don't bother feeding this fish since its not going to eat, and the added waste will just degrade the QT.
When you move the fish to the QT, don't remove him from water by netting. Get him into a submerged zip-lock, keeping him in water, then make the move. Since the water in QT is the same as water from display, little acclimation is necessary.
Don't forget you may need to heat the QT to match the temp in the display.
Don't leave the fish in dark. A bit of room lighting will work.
A rubbermaid is a good idea, and use egg crate for the cover. You don't want the fish in complete darkness, as sick fish are more likely to pass in darkness than not.
You will need to prepare a large amt of freshly well mixed salt water. Use the water in your display for your QT, but then replace the new salt water in the display. Cover the bottom of the rubbermaid with a very small layer of live sand from your display. This should just be enough to have a bit of sand, but not a thick layer.
Keep the water movement in the QT going throughout the system, and surface of the top should be rippling. If you can get a small pump that will shoot water up from the bottom of the rubbermaid to the surface that would be best. But don't make circulation so strong the fish is being banged about.
Be sure to add either fake rocks or PVC in for the fish.
At this point, don't bother feeding this fish since its not going to eat, and the added waste will just degrade the QT.
When you move the fish to the QT, don't remove him from water by netting. Get him into a submerged zip-lock, keeping him in water, then make the move. Since the water in QT is the same as water from display, little acclimation is necessary.
Don't forget you may need to heat the QT to match the temp in the display.
Don't leave the fish in dark. A bit of room lighting will work.