Ich disease and its treatment in aquaculture and ornamental fish culture

Ichthyophthirius multifiliis is a protozoan parasite that can cause catastrophic damage to fish farms and aquariums. This parasite can be transferred to a pool of fish, tanks, or other aquariums by introducing new fish or using equipments previously used in another farms. Therefore, the most effective way to prevent this disease is to use quarantine regulations. When this organism enters a system, during a short time cause severe deaths so that in severe infections, disease control is impossible and we ought to expect 100% fish losses. Unlike most parasitic diseases where the decision to treat sick fish depends on the severity of the infection, the treatment of fish infected with Ich parasite, although only one parasite has been observed in these fish, should begin immediately because of the speed of reproduction. One-step treatment is not sufficient to treat this disease because the life stage on the body of the fish (trophont) and the cystic stage in the environment (tomont) are resistant to chemicals and the only infectious Tront stage that is sensitive to treatment. Repeated chemical treatment can disrupt the life cycle and its spread. Fish surviving from Ich infection may act as parasite reservoir and may infect other fish. Ich can be controlled quickly and conveniently, but the cost of treatment for large farms will be high given the cost of chemicals and the amount of labor involved. Adequate attention to management methods, such as quarantine and multiple treatments when the disease occurs, can minimize the costs of the disease.