Fish community biomass (B), and abundance (A) and production (P) of the Volynka Stream, Bezdrevsky Brook and Vltava River influenced by organic waste waters were estimated. The dominant trout population was strongly affected by pollution: values of A, B, P decreased from 1264 inds.ha-1, 85.6 kg.ha-1 and 76.2 kg.ha-1 to 92 inds.ha-1, 9.8 kg.ha-1 and 5.9 kg.ha-1 in Volynka Stream; from 10 496 inds.ha-1, 200 kg.ha-1 and 215 kg.ha-1 to 0 in Bezdrevsky Brook; for the Vltava River we do not know the unpolluted state but the following values of A, B and P were found below the inflow of pollution: 66 inds.ha-1, 5.6 kg.ha-1, 4.9 kg.ha-1. The trout population regenerates after 5-6km in Volynka Stream and the Vltava River. In the Bezdrevsky Brook the trout population was replaced by cyprinids and perch Perca fluviatilis. The growth rate of trout in polluted sections was obviously higher, the proportion of younger age groups lower.