|Have your fish been suffering with a bout of ich that simply refuses to go away? Have you tried everything, but it just seems to come right back? Has the thought crossed your mind that your heater may be the problem? "Value heaters" or heaters that are improperly sized for the aquarium may lack the ability to properly regulate and maintain a consistent water temperature, causing it to fluctuate several degrees over relatively short periods of time. Abrupt changes in temperature are extremely stressful to fish, and stress can lead to a weakened immune system. Once compromised, a fish's immune system is unable to defend itself against illnesses and parasitic infections, such as ich. To ensure stable temperatures within your aquarium and reduce the amount of stress placed on your fish, invest in a quality heater, thermometer and a backup heater in case of an emergency. Select a heater that is the proper size for your aquarium, the rule of thumb is to allow 3 to 5 watts per gallon of water. Creating and maintaining a stable environment, especially consistent water temperature, is one of the easiest ways to create a healthy, happy and comfortable environment for your fish.