Dermocystidium is a genus of protist belonging to the Mesomycetozoea and included in the order Dermocystida (Blazer, Hitt, Snyder, Snook, & Adams, 2016; Glockling, Marshall, & Gleason, 2013; Rowley et al., 2013). The genus is characterized by a small spherical spore with a nucleus in the periphery and a prominent refractile body in the centre. Dermocystidium infections have been described in amphibians (Feldman, Winsatt, & Green, 2005; Gonz�alez-Hern�andez et al., 2010; Pascolini et al., 2003), but the majority of the observations concern both freshwater and marine fish infections. There are more than 20 species of Dermocystidium infecting fish (Hassan, Osman, & Mahmoud, 2014). In some cases the parasites were described from farmed fish like Oreochromis niloticus (El-Mansy, 2008), Silurus meridionalis (Zhang & Wang, 2005), Anguilla anguilla (Wooten & McVicar, 1982), while in others they were reported from wild hosts like Perca fluviatilis and Gymnocephalus cernuus (Pekkarinen & Lotman, 2003), Cottus gobio (Feist, Longshaw, Hurrell, & Mander, 2004), and Trichomycterus sp. (Eiras & Silva-Souza, 2000), later is the only report in Brazilian fish. Most of the species are found in the gills, skin and cornea of the eye causing grossly visible cysts of different sizes and shapes, however systemic infections were also observed (El-Mansy, 2008; Hassan et al., 2014), and some cases of mortality were attributed to infection (Hedrick, Friedman, & Modin, 1989; Langenmayer et al., 2015; Olson, Dungan, & Holt, 1991; Olson & Holt, 1995; Zhang & Wang, 2005). The life cycle of Dermocystidium was studied by some authors (Lotman, Pekkarinen, & Kasesalu, 2000; Pekkarinen & Lotman, 2003)