Occurrence of Trichodina pediculus Ehrenberg, 1838 in Dgal Wielki Lake

Parasitological investigation were performed in Dgal 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.

Variability of the reproductive system of Piscicola fasciata (Kollar, 1842 (Hirudinea, Piscicolidae)

The studies on the reproductive system of P. fasciata were based on 43 specimens. Two main types of the reproductive system can be distinguished in the studied population. Two types of reproductive system were the most frequent (20.93% each): with symmetrical ejaculatory ducts without a loop and symmetrical seminal vesicles reaching the end of the first pair of testes, situated next to the testes (adult individuals) (fig. 23) and with symmetrical ejaculatory ducts without a loop (fig. 21) and symmetrical poorly developed seminal vesicles situated asymmetrically anterior to the first pair of testes (juvenile individuals). The structure of the reproductive system corresponding with the description of the type specimen (BRUMPT, 1900) was not observed in the studied population.