At present,there are three different hierarchical levels at which parasites could be used as potential biological indicators. First, it is the level of an individual; second, the level of a population and third, the level of a community. The examination of attachment apparatus of selected parasites revealed abnormal morphological changes in relation to environmental pollution. As a result of various types of environmental pollution, a decrease in parasite species richness, as well as an increase of homogeneity of parasite distribution within the component community were recorded. Based on species richness and heterogeneity measures, the fractionation of parasite component community appeared to be taxonomically and ecologically reasonable. Relationship between composition and structure of parasite infracommunity with respect to the level of chemical contamination and biochemical markers of exposure in individual fish were found. It is evident, from a detailed analyses of hierarchically structured data, that parasites of fish seem to be a perspective nonspesific indicator of freshwater ecosystem integrity.