EN
Parasitological investigation were performed in Dgał Wielki, occurrence T. pediculus Ehrenberg 1838 on the roach gills were recorded. On the 277 examined roach in 9 roach specimens T. pediculus were found. Prevalence of roach infection was 3.25%, mean intensity 3.5 and abundance 0,11 parasite per number of fish examined. T. pediculus were found on fish in May and June.