Cryptocaryon irritans is a species of ciliate protozoa that parasitizes marine fish, and is one of the most common causes of disease in marine aquaria. The symptoms and life-cycle are generally similar to those of Ichthyophthirius in freshwater fish, including white spots, on account of which Cryptocaryon is usually called marine ich. However, Cryptocaryon can spend a much longer time encysted. Useful treatments of Cryptocaryon irritans are copper solutions, formalin solutions, and quinine based drugs (such as Chloroquine Phosphate and Quinine Diphosphate).