I just got home from walking the dog, sat down to post those pics, and the tangs are nipping at the algae clip! Most of the algae sheet had broken off and they were nipping at what remained in the clip. I took the sheet that was floating around out of the tank but there's a bunch of tiny floaters that are still in there. Two of the tangs look great but one has a bit of a sunken stomach. The once with a sunken stomach is nipping at the clip, too, so hopefully tomorrow it'll look better.
Since they all look very healthy, I began lowering the salinity straight away. The SG is at 1.017 right now. I will go the rest of the way down to 1.009 by tomorrow night.