Spermatozoa of the teleost fish Perca fluviatilis (perch) have the ability to swim for more than two hours in saline solutions

Spermatozoa of the perch, a teleost fish with external fertilization are motile for < 90 s in water which is similar to other teleost fresh water fish species investigated so far. When motility was activated in a saline solution consisting of 75 mmol/l NaCl, 5 mmol/l KCl, 1 mmol/l MgSO4, and 1 mmol/l CaCl2 it was prolonged to > 2 h at 4 °C. The initial motility rate 10 s after activation was 72.6 ± 17.6% and the swimming velocity 126.4 ± 14.2 μm/s. After 4 min motility dropped to 42.8 ± 14.0%. Thereafter, the motility rate and swimming velocity remained constant for > 2 h (41.6 ± 10.0% and 102.2 ± 14.3 μm/s). This is the first report demonstrating that teleost fish spermatozoa are able to swim in saline solutions and without exogenous energy supply with constant high velocities and unchanged motility parameters for several hours.