An ectoparasite leech Piscicola geometra were found on female roach (Rutilus rutilus) between the anus and lateral line during the biometric measurements for the purpose of monitoring the fish population in Uluabat Lake. P. geometra was previously reported on Carassius gibelio and Tinca tinca from Lake Uluabat. It was understood with this case report that R. rutilus also is a host fish for P. geometra in Uluabat Lake.