Water temperature can be gradually raised to 90°F, maintained there for 24 hours, and then gradually dropped to 70°F for 48 hours. The infective juveniles (tomites) will be killed while the water temperature is at 90°. When the temperature is dropped, the adult organisms will fall off the fish and begin to reproduce. As the young begin to emerge 48 hours later, the temperature is again raised to 90°F, causing them to die. Repeating this process continuously (24 hours at 90° F followed by 48 hours at 70° F) for two weeks should control the disease. Cleaning the tank every second day will help remove cysts before they rupture and thereby help to prevent completion of the life cycle. If you decide to use temperature to control "Ich" in your home aquarium, be sure that the type of fish in your tank can tolerate the temperature extremes involved