This study was carried out to determine the changes in spermatological characters of Rainbow Trout (Oncorhynchus mykiss, W.) semen in regular stripping.

In this research, 30 male adult Rainbow trout fed on pellet feed were used. It was stripped fortnightly during four months. Before stripping, the adult male Rainbow trout were anaesthetized in 0.3 mg phenoxyethanol / lt. Semen was collected manually by applying pressure to the abdominal cavity. The average values for semen volume, semen pH, spermatozoa concentration and motility were 5.49±1.11 ml, 5.66±0.63, 9.28±1.29x 109/ ml and 66.86±4.57 % respectively.

In conclusion, an increase was observed in semen volume, semen pH, spermatozoa concentration and motility at the beginning of stripping season followed by a gradual decline, later. This declines were found statistically significant (p<0.01).