Myxozoans are a group of diverse, spore-forming metazoan microparasites bound to aquatic environments. Sphaerospora dykovae (previously S. renicola) causes renal sphaerosporosis and acute swim bladder inflammation (SBI) in juvenile Cyprinus carpio carpio, in central Europe. A morphologically similar species with comparably low pathogenicity, S. angulata has been described from C....