In recent years, tannin has been used to decrease adhesiveness of walleye eggs during artificial propagation. Spermatozoa samples were taken from ripe male walleye to investigate the effect of tannin concentrations on spermatozoa motility or fertilizing capacity. A statistically significantrelationship in reduction of spermatozoa motility with increasing tannin concentrations resulted. Consequently, tannin does influence the fertilizing capacity of walleye spermatozoa and hence during artificial propagation should not be added until the second rinse after fertilization.