First reported occurrence of Thelohanellus oculileucisci [Trojan, 1909] [Myxosporidia] in Leuciscus leuciscus [L.] and L.idus [L.] in Poland

A myxospridian, Thelohanellus oculileucisci (Trojan, 1909) was found in the vitreous body of an eye of a dace, Leuciscus leuciscus (L.) from the river Bug near Kamieńczyk, and Leuciscus idus from the river Vistula near Warszawa. The vegetative forms - several oval to round cysts, 0.4-0.5 mm in diameter, contained numerous, pear-shaped spores with one polar capsule at the narrower end. The parasite has not been noted until now in fish in Poland.