Crayfish plague, Aphanomyces astaci, is a water mold that infects crayfish, most notably the European Astacus which dies within a few weeks of being infected. When experimentally tested, species from Australia, New Guinea and Japan were also found to be susceptible to the infection.
Aphanomyces astaci commonly referred to as crayfish plague is an oomycete or water mould that infects only crayfish species. It is endemic of North America and is carried by North American crayfish species; signal crayfish Pacifastacus leniusculus, Procambarus clarkii and Orconectes limosus. A. astaci was introduced into Europe through imports of North American species of crayfish. Native European crayfish populations are not resistant to this oomycete. It has since devastated native crayfish stocks throughout the continent.