Sphaerothecum destruens (the rosette agent) is a parasite of fish.[1][2] It was first discovered in the United States in association with invasive species including topmouth gudgeon but was found to be the causative agent of a disease in the UK affecting salmonid species such as Atlantic salmon and brown trout. It is thought to pose more of a risk in Europe than in the USA as native species there are more susceptible to the parasite. The disease causes high rates of morbidity and mortality in a number of different salmonid species and can also infect other UK freshwater fish such as bream, carp and roach.[3] The genus Sphaerothecum is closely related to the genera Dermocystidaium and Rhinosporidium.[2]
Source: Wikipedia (https://en.wikipedia.org/wiki/Sphaerothecum_destruens)
