Cryopreservation of Waigieu Seaperch (Psammoperca Waigiensis) Sperm

BACKGROUND: The cryopreservation protocols have been applied for sperm prevervation of many fish species, but have not been developed for Waigieu seaperch Psammoperca waigiensis, an important aquaculture species in Vietnam. OBJECTIVE: The objectives of this study were to find the best cryoprotectant, extender, freezing method and dilution ratio for sperm cryopreservation of Waigieu seaperch. MATERIALS AND METHODS: An effective protocol was established by comparing different cryodiluents created by mixing various cryoprotectants and extenders. The different freezing methods and dilution ratios were also used in an effective protocol. The motility (MOT), straight-linear velocity (VSL) and fertility rates of post-thawed sperm were comparable to that of fresh sperm. RESULTS: The results indicated that at ratio of 1:3 in cryodiluent contained ASP (artificial seminal plasma) as extender supplement 10% DMSO as cryoprotectant and cryopreserved with the freezing method as two steps, reached the best MOT and VSL of post-thawed sperm. The fertilization rate and hatching rate of the post-thawed sperm cryopreserved for 1 week, 1 month, or 1 year in liquid nitrogen (66.93 ± 0.93% and 44.16 ± 1.47%, 65.40 ± 1.11% and 43.88 ± 1.54%, or 65.13 ± 1.31% and 43.24 ± 1.41%) were similar to that of fresh sperm (68.67 ± 1.27% and 45.12 ± 1.92%). CONCLUSION: Using cryodiluent contained the ASP as extender and 10% DMSO as cryoprotectant to semen at the ratio of 1:3 (v/v) in the freezing method as two steps (-76°C for 5 minutes and -196°C) is an effective protocol for cryopreservation, especially hatching success of egg fertilized by post-thawed sperm of Waigieu seaperch.