Establishment of medium for laboratory cultivation and maintenance of F redericella sultana for in vivo experiments with T etracapsuloides bryosalmonae ( M yxozoa)

The freshwater bryozoan F redericella sultana ( B lumenbach) is the most common invertebrate host of the myxozoan parasite T etracapsuloides bryosalmonae , the causative agent of proliferative kidney disease in salmonid fish. Culture media play an important role in hatching of statoblasts and maintaining clean bryozoan colonies for M alacosporea research. We developed a novel culture medium, B ryozoan M edium C ( BMC ), for the cultivation and maintenance of F .  sultana under laboratory conditions. Statoblasts of F . sultana were successfully hatched to produce transparent‐walled, specific pathogen‐free ( SPF ) colonies that were maintained >12 months in BMC at pH 6.65. T etracapsuloides bryosalmonae was successfully transmitted from infected brown trout, S almo trutta L ., to newly hatched F . sultana colonies in BMC , then from the infected bryozoan to SPF brown trout. This study demonstrated the utility of BMC ( pH 6.65) for hatching statoblasts, long‐term cultivation of clean and transparent bryozoan colonies and maintenance of the T etracapsuloides bryosalmonae life cycle in the laboratory for molecular genetic research and other studies such as host–parasiteinteraction.