On the original question from CS31. Have you considered AMYLOODINIUM. This disease is sometimes incorrectly call saltwater ich. Properly identified as Amyloodinium Ocellatum, it is also know as Oodinium ocellatum, coral fish disease, or velvet disease. It is extremely difficult to recognize until it becomes advanced, because the individual trophonts are too small to be distinguished with the naked eye. Often no signs of the disease are noted before losses begin. This disease has no equal in the speed and presistence with which it causes havoc in a closed system.Behavioral signs of an Amyloodinium infection will likely be failure to feed, a rapid respiration rated (greater than about 80 respirations per minute for clownfishes), swimming into the water current, and scratching in an unsuccessful attmept to rub the gilol irritant off. Through a microscope you may note the parasites as small spheres. Blemished cloudy areas (most notable on the fins) or excess mucus at particular places on the fish may be noted in advanced stages. the cloudy aareas are the spots that have been liquefied by the parasite's feeding. The treatment for this is lowering salinity, cleaning and vacuuming system, and if by day 3 it presists, to start a copper treatment. Specific gravity can be lowered to not lower than 1.010-1.012 . the depressed specific gravity should be kept for a couple months but if the fish is not better by day three the treatment with copper to 0.20 mg/L and begin bringing the tanks specific graity to above 1.018 take a day or more to bring up the specific gravity. days 4 through 13 monitor the copper every day with a test kit and add more as needed to keep the lever at 0.20 mg/L. The treatment is ineffective if the copper level drops. Monitor the tank for ammonia. Monitor the fish. Protracted treatment of Amphriprion ephippium and A. bicinctus seems to kill them or at least to invite tears in their skin and subsequent bacterioa infections. Treat these species with copper, under carful scrutiny and remove the copper early and add and antibiotic if needed. Day 14 remove the copper using carbon, poly filter pads, or water changes.
I do not know if this is what you have so proceed slowly and make sure you identify the disease 1st before treating. naturally you cannot use copper in the main tank. If you want to keep clown fish I would recommend the following book: Clownfishes by: Joyce D. Wilkerson ISBN-1-890087-04-1 good luck.