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The objective of the research was to test the effect of iron and aluminium coagulants commonly used for lake re-cultivation, on the pike sperm motility and fertilisation. The coagulants caused changes in the analyzed hydrochemical parameters of the water such as: Fe, Mg²⁺, TSS, SO₄^2- and Cl^-. Selected parameters of sperm motility: MOT, VCL, VSL, VAP, LIN were estimated using CASA. The sperm motility at the moment of activation was the highest in the control sample. With increasing the time of exposure the proportion of sperm motility in the analyzed semen decreased. In the samples with coagulants the values of MOT, VCL and VSL were smaller than in the control sample (statistically significant differences between the control and the samples with PIX and PAX were recorded in the 25^th-30^th second after activation). The percentage of fertilised eggs was the greatest in the control sample and in the PAX®18 sample (73.11 and 70.42%, respectively), whereas in the PIX®113 it was less than that (54.88%). The shortest larvae were those in the sample with coagulant PIX®113. In the samples with PIX®113 and PAX®18 the survivorship of embryos compared to the control sample was the smallest (43.10 and 51.61%, respectively and control 67.60%) and the proportion of malformed larvae was the highest (34.82 and 24.52%, respectively and control 15.17%).