Summary Cylindrospermopsis (Raphidiopsis) raciborskii is an invasive, filamentous, nitrogen‐fixing cyanobacterium that forms frequent blooms in freshwater habitats. While viruses play key roles in regulating the abundance, production and diversity of their hosts in aquatic ecosystems, the role(s) of viruses in the ecology of C. raciborskii is almost unexplored. Progress in this field has been hindered by the absence of a chara...