In this study, changes of pH, ionic (Na+, K+, Ca2+, and Mg2+), biochemical (total protein, glucose, and cholesterol) compositions of seminal plasma, sperm motility traits (percentage of motile spermatozoa and sperm movement duration), and sperm production characteristics (sperm volume, spermatocrit, and sperm density) were studied in Caspian roach, Rutilus rutilus caspicus, during spawning migration. Sperm of 10 males was collected three times during the spawning migration (in February, March, and April). The results showed that sperm motility parameters (percentage of motile spermatozoa and sperm movement duration) changed significantly (P < 0.05) during the reproductive season, but sperm density, spermatocrit, and sperm volume did not show significant differences during spawning migration. Analyses performed at each sampling time (February, March, and April) showed significant differences (P < 0.05) in calcium, magnesium, potassium, and cholesterol, whereas there were no significant changes in Na+, pH, total protein, glucose, and cholesterol.
