Formicki K., Kowalewski M., Sobociński A., Winnicki A., 1993. Sperm quality of grayling (Thymallus thymallus L.) under natural conditions and in ponds. Acta Ichthyol. Piscat. 23 (2): 139-145.

Spermatozoa quality of two grayling (Thymallus thymallus L.) populations: free-living and bred in ponds, was compared. The percentage of spermatozoa activated upon contact with water, time of progressive movement (turbulent and smooth phase), time of oscillatory movement and the spermatocrit were determined. Males living in a river, as compared with those reared in a pond, displayed a significantly higher percentage of activated spermatozoa, whereas both populations did not significantly differ in spermatozoa motility and spermatocrit.