Henneguya zschokkei

Henneguya zschokkei or Henneguya salminicola is a species of a myxosporean endoparasite. It afflicts several salmon and trout in the genera Oncorhynchus and Salmo, where it causes milky flesh or tapioca disease. H. zschokkei does not require oxygen to survive and is notable for being one of the few multicellular organisms in the animal kingdom to rely on an exclusively anaerobic metabolism. It is also notable for its lack of both mitochondria and mitochondrial DNA.