The water was getting down to the low 60's, and his behavior is pretty much normal again, so I put him back in with the others. I also bought some Maroxy today.

I figure if anyone else gets sick (which seems unlikely at this point), I'll just put some in. The salt seems to be working, at least behaviorally. The discolored skin is still there, and isn't getting worse (or better), but he is way more active (swimming quickly, digging about, and only spending time at the surface to come up for a breath. He also escaped my grasp a lot more energetically when I was returning him to the original tank.

If his discoloration remains unchanged, how long should I leave it before putting in Maroxy? Or should I just put some in now for the hell of it, to be safe?