This study examined the influence of ferric and aluminium coagulants (PIX 113 and PAX 18) and ferrous sulphate, used for lake restoration, on growth and mortality of cladocerans Daphnia magna Straus. We observed that addition of these coagulants in concentrations comparable to those used in various restored lakes reduced significantly the increase of Daphnia biomass comparing to the results obtained in the samples without coagulants. This phenomenon was directly proportional to the coagulant concentration. Ferrous sulphate turns out to have been the most toxic compound, while PAX 18 was the less harmful. Ferric coagulants also caused crustacean mortality ranging from 4 to 36%.