We had a parasite in our display tank, and our survivors, including our Yellow Tang, have been in QT for 7 weeks.We treated with copper for 14 days. Things went well for about 3 more weeks, then the fish in one of our QT tanks started becoming really stressed. The Tang stopped eating, and wouldn't come out from under a rock. We discovered it was a pH problem, and have added a pH buffer and have been running an air stone for the past week.For a few days the Tang seemed to do better (the pH has been close to 8); she came out and began eating again. However now she is not eating, and isn't really swimming, instead she is floating around the tank with the current, bumping into rocks and other things.We tried soaking her seaweed in garlic last night, and have tried feeding flakes and mysis shrimp. She is emaciated and we are worried about losing her soon. We've had her for 3 months. She is currently in a 10 g tank with a Firefish.