Yes, treat your tank with copper, and maintain cooper levels at theraputic levels for a month AFTER all signs of disease disappears. Get a test kit that measures copper levels and keep it at the level recommended on the medication label. Also, if your sick fish appears fairly healthy still, you can give it a "freshwater" dip. Here is the procedure: Get a gal of distilled water from the grocery store and prepare a bathing container for your fish [a bucket or container that has NEVER been used for anything; in other words, a fish only container] Make sure the temp of the water is the same as your tank. Then put your fish in this bath for 1 minute. Return him to the tank. Use this procedure only if the fish still has the white spots on it. It is important to maintain the copper treatment in the tank even after everything looks normal again. Ick [white spots] drops off the fish and becomes free-swimming in the tank, and will re-invest your pets if you don't maintain the medication for several weeks. A formalin bath is basically the same thing. Prepare a separate container for your fish with water from your tank and include high dose of formalin in the cantainer. Follow the recommendations on the medication bottle! Let the fish swim in this [usually about an hr, but don't kill your fish with too high a dose of formalin!], then return him to the tank. I don't recommend a freshwater bath with formalin in it, as this is very stressful indeed! Also, copper in the tank only if your tank has NO invertebrates or live rock. Copper kills invertebrates. The "bath" treatments here are very stressful for fish, so you must be cautious, and you must keep your eyes on the fish at all times ready to return him to the tank if stress is too high. [Get a UV sterilizer, it's worth the investiment not go thru these common parasitic headaches!]