Ich (ick) is the most common disease of all freshwater and marine aquarium fish. Anyone that keeps fish for any period of time will eventually have fish that develop ich. Many hobbyists consider this disease to be just a common nuisance but the reality is that ich is probably responsible for more fish deaths than just about any other disease. There are several effective treatments for ich, but if they are not administered correctly, they can cause serious problems with your fish and tank inhabitants. This article will help explain the source and cause of ich as well as giving treatment options and prevention strategies.
What is ich?
Ich is a protozoan disease that is often called 'white spot disease.' The scientific name for the disease is ichthyophthiriasis and the causative agent is Ichthyophthirius multifiliis. It is wide spread in all freshwater fish but appears to be more common in aquarium fish, possibly due to the closer contact and stress involved with aquarium species.
Why fish get ich
Ich is so widespread that many experts feel that it is present in the environment of most aquariums, especially in larger holding tanks, rearing ponds of breeders, collectors, and wholesalers. In fact, just about every aquarium fish will come into contact with this protozoan at several times in its life. Because it is so widespread, most fish have developed a good immune response against the disease to allow them to fight off the protozoan infection before it ever causes any symptoms. Captive fish that develop ich usually get the disease when their immune systems are not functioning as well as they should be because of stress. We know that stress lowers the immune response and when fish are stressed that is when ich is most prevalent.
There are many causes of stress in a fish's life, many of which can be made worse or better by the owner. Water temperature, water quality, tank inhabitants, improper diet, and a variety of other factors all contribute to stress, but one of the most severe causes of stress occurs during shipping and handling of a new fish. Whether coming from the wild or farm-raised, the handling and shipping of the fish from their origin to a wholesaler, then to a retailer, and finally to your home is extremely stressful. With the widespread prevalence of ich, it is no wonder that many newly purchased fish are affected.
Identifying ich
The symptoms of ich are very evident and usually include characteristic white spots on the body and gills. In some infections, the ich organisms will only be found on the gills. As the disease progresses, the fish will become more irritated and may try to rub or scratch against the sides and bottom of the tank. The disease may then cause respiratory distress, severe agitation, loss of appetite, and eventually death.
This disease is often identified based upon history, symptoms, and the presence of white spots, but if there is any question, it can be identified microscopically. A lesion can be scraped and viewed under the microscope to reveal a rather large cyst between .5 and 1.5 mm in diameter. It also has a very characteristic large horseshoe-shaped nucleus.