Ich is caused by an external parasite that causes multiple white spots on your freshwater fishes' skin and gills. This is a common parasitic infection of freshwater fish and is one of the few fish parasites that can be seen with the naked eye.

How does ick start?

Ich (pronounced "ick") short for Ichthyophthirius, is an external parasite often referred to as "white spot disease." Aquarium fish manifest symptoms when under stress or housed in improper aquarium conditions. Most often, it is brought on by fluctuating aquarium temperatures.

Can a fish survive Ich?

Fish that survive mild infections can develop immunity. There are currently no drugs or chemicals that kill Ich while it resides in the fish skin or gills; they can only kill Ich when the parasite is in the water, and therefore all current therapies require a cyclical re-treatment program.