Optimization of Sperm Management and Fertilization in Zebrafish [Danio rerio (Hamilton)]

There were over 70% of spermatozoa activated, because they were contaminated with urine or excrement. The movement of spermatozoon in water was propagated along the flagellum at 16 s after sperm activation, then damped from the end of the flagellum for 35 s and fully disappear at 61 s after activation. For artificial fertilization, milt must be added to an immobilizing solution, which stops the movement of sperm and keeps the sperm motionless until fertilization. E400 and Kurokura as isotonic solutions were shown to be suitable extenders to store sperm for fertilization for 6 h and E400 to store sperm for 12 h at 0-2°C. Sperm motility decreased only to 36% at 12 h post stripping for E400 extender and to 19% for Kurokura extender. To achieve an optimal level of fertilization and swim-up larvae rates, a test tube with a well-defined amount of 6,000,000 spermatozoa in E400 extender per 100 eggs and 100 µl of activation solution has proved to be more successful than using a Petri dish. The highest fertilization and swim-up larvae rates reached 80% and 40-60%, respectively, with milt stored for 1.5 h in E400 extender at 0-2°C.