white spot

1) ich (a contagious disease of aquarium and hatchery freshwater fishes, caused by a large protozoan (Ichthyophthirius multifiliis or I. hoferi) and characterized by small white to greyish pustules on the skin and eyes, the encysted mature parasite. Fish become hyperactive, show flashing and may cut themselves on sharp objects as the parasites cause irritation. Severe infections cause respiratory problems and death. Various chemical additives such as malachite green, formalin and methylene blue can be used to treat the aquarium water. Removal of fish from the aquarium will interrupt the parasite life cycle as encysted trophozoites settle to the aquarium bottom and divide into tomites or theronts which re-infect fish skin. Also called white spot and ichthyophthiriasis).