Ovipleistophora diplostomuri (Microsporidia) is an obligate parasite of fish and trematodes in the US. In April 2019, an individual crayfish, Procambarus bivittatus (Escambia River, Florida), with a high-intensity microsporidian infection was delivered to the Emerging Pathogens Institute. Histological analysis determined that infection was restricted to the muscle tissue. Molecular diagnostics (PCR) provided 952 bp of the parasite SSU (18S) sequence. The isolate was 99.16% similar to O. diplostomuri identified from blue gill and their trematode parasites in Washington, USA. This discovery increases our understanding of Microsporidia within aquatic trophic networks, supporting the theory that the Ovipleistophora share complex relationships with vertebrates, invertebrates and helminth parasites.