EN
This work consisted in studying the frequency of deformations of the attachment organ in specimens representing the family Diplozoidae, occurring in roach, common bream, and white bream from live different water bodies. These water bodies differed in morphometric parameters, levels of eutrophication, and character of their pollution. The presence of three types of deformation was stated. The most common were deformations of type II (morphological changes of clamps, such as sclerite deformation, incomplete sclerite separation or sclerites missing altogether in a clamp), while less frequent were those of types I (chaoges in the size of clamps not associated with the structural changes) and III (missing clamps in a set). Most frequently anomalies of the attachment organ were stated in polluted Łyna River, polluted Wulpińskie Lake, and in dystrophic Warniak Lake. Less frequent were anomalies in less eutrophied lakes Dgał Wielki and Ukiel. Also the prevalence values of those parasites were the highest in the polluted water bodies. The present study suppons believes of other authors, that both infection parameters of Diplozoidae affecting fishes and deformations of monogeneans' attachment apparatus can be treated as indicators of environmental pollution.