The reason you use a fresh water dip is to help insure your not putting any hitchhikers in your tank that you don't want like I have had back when I didn't I got Flat worms and had a nice little Monti eating Nudi. I couldn't get off of the monti because he was in between ridges so I put it into fresh water and it dropped right off. I don't do fish either because it makes a stressful situation even more stressfull I dip all of my corals, including my Xenia's even when I move them from tank to tank when thinning them out one tank. I use a fresh water dip using this receipie and I have never had any problems so I really don't think the Dip did anything. My Xenia's will however scrunch up to a fraction of their original size occasionally and remain that way for several days. Be patient I am sure it will open back up. I wold however watch them and if they start looking like thay are melting remove them from you tank right away because they are dying.