What's the best way to treat ich?

2) Use a medication containing malachite green and formalin. (QuickCure or Rid-Ich are two good brands.) This is the most effective medication, and the safest for your plants, biological filter, and invertebrates. If you have delicate fish like tetras or loaches in the tank, use half a dose twice a day (once in the morning, once in the evening), instead of putting in the whole dose at once.

3) Treat for at least two weeks. Ignore the directions on the package. Instread, treat daily until all spots are gone. Then treat every three days, for another two weeks. Yes, even if the ich seems to be gone. This is necessary because ich has a complicated life cycle, and the medicine can only kill one stage of it.

Details:

Some do's and don'ts...

Don't add salt. It's not necessary with today's medication, and some plants won't tolerate it. Instead, add Novaqua or Stresscoat to soothe the fishes' skin.

Don't raise the temperature, unless you're keeping a discus tank. It's not necessary, and can be harmful. Raising the temperature needlessly stresses the fish. Warm water holds less oxygen, and the fish might have ich on their gills, impeding their breathing. In addition, raising the temperature speeds up the life cycle of the ich parasite, meaning it will get a lot worse before it gets better - perhaps fatally so. (However, if you're keeping discus or other fish that like high temperatures and don't tolerate chemicals, raising the temperature to about 95F will kill ich outright, with no need for medication.)

Do turn off the tank lights for a few days. Ich parasites need light in order to find their hosts, so leaving the tank lights off will slow the spread of the disease. The fish will also be less stressed with the lights dimmed. The plants will be all right if the lights are only off for a few days.

Do daily 50% water changes while treating for ich, vacuuming the gravel if possible. This physically removes the ich parasites, and keeps medication from building up too much. Schedule the water change for just before you put in one of the medication doses.

Don't use copper-based meds in a planted tank. (Coppersafe, Aquarisol, etc.) Copper is poisonous to plants, and to invertibrates such as snails and shrimp.