I know the urge to keep checking on it is great but keep the lights off. Even when doing the small water changes. Don't remove the blanket either just pull back a corner and remove the water from one corner. You want as little stress as possible. Leave the live foods in at all times. If you feel the need to check just lift a small corner and peek in. Personally I wouldn't even treat with Prazi or salt, but that is me. It can further stress and reduce O2. He is malnurished from the capture, holding and transflight to states. The stinger is irrelevant unless there is fungus and it doesn't appear to have any.
Water change, Water change Water change in small amounts.
GL
Water change, Water change Water change in small amounts.
GL