I have a purple tang with what seems like a rectal prolapse that we first noticed when we got back from a weekend away, last night. Not eating today. It's a relatively new addition (been in tank for 2 weeks) and was the first to break with what we think is ich last week. We put the whole display tank into hyposalinity at 13.5 ppm a few days ago because we were going to be away for the weekend and didn't want to put all fish into 20 gal quarantine tanks (fish only right now). Recommendations for what to do?