I just got a new Rectangle Trigger from my local pet store, He is about 5 inches long, I added him into my 90g tank very slowly, first acclimating him to the temperature and then the water. The process took about an hour, However after a few days i noticed he had ich, day 3 just a few white spots on the fins, and day 4 it was all over the fish, BUT, Day 5 (Today) I noticed there was only a few spots on his fins??? It seems to be going away on its own. I called the store where I got him and they recommended that i do a fresh water dip with the fish. What do you guys think about taking this approach? Thanks for any suggestions. also, it is a relatively new tank and there is no coral in it at the moment.