Ich, short for Ichthyophthirius multifiliis, is a caused by parasitic organism that commonly attacks freshwater fish. It is most likely encountered by aquarium fish; it is also the largest known parasitic protozoan found on fish. The actual disease, referred to as Ich or white spot, can become serious in a small environment and will travel quickly throughout a colony; it is responsible for the most fatalities among freshwater aquarium fish.
During the process, rapid reproduction of the disease causing cells attack the exterior of the fish. It eventually digs until it reaches open area under the scales or the gill plate. Once one fish is infected, ich begins spreading to others. The entire life-cycle takes about seven to ten days to complete.
Preventative measures against ich include buying fish that are assuredly healthy and come from reputable dealers. Quarantine fish that appear unhealthy, as well as new arrivals; this keeps one new fish from infecting the main aquarium. Keeping water conditions at a high quality level will also help. Avoid overstocking the population. Adding aquarium salt may also be a successful method for preventing ich.
Ich outbreaks usually occur when new fish are introduced or during times of stress. Latent infections can also be brought about by elevated ammonia or nitrate levels, as well as sudden changes in temperature; a sudden chilling of the fish, which can easily occur when they are being transported, is often sufficient to take the parasite from its latent state to the reproductive phase.
Warning signs can include behavior such as loss of appetite, frequent hiding, flashing or rubbing and scratching against objects.
The disease manifests in the form of characteristic white spots on the side of the fish; these cells contain trophozites which feed on host tissues. These spots may also appear on the fins. The eyes tend to become cloudy and the gill infection will cause breathing at the surface and fast respiration.
Treatments vary and involve three major methods. They can be done using heating elements, salt, chemical additives or combinations of the three. It can also be treated with a transfer method, by placing the infected fish in a quarantine tank until the symptoms have subsided. If the disease is diagnosed early and effectual treatment is applied, the outlook is excellent. However, if the infestation is at an advanced stage, mortalities should be expected. Note that when a fish has been cured from ich, it will usually form immunity to the infection.