• Cryopreservation;
  • extender;
  • cryoprotectant;
  • sperm;
  • Mekong catfish;
  • Pangasius bocourti


The effects of three extenders (Ginzburg fish ringer, Calcium-free Hank's balanced salt solution, C-F HBSS and sodium chloride, 0.9% NaCl) and four cryoprotectants (dimethyl sulphoxide, DMSO; dimethyl acetamide, DMA; methanol, MeOH and glycerol) in different concentrations (5%, 10% and 15%) on the motility, viability and fertilization rates of Mekong catfish (Pagasius bocourti) sperm were investigated. Sperm samples were transferred into 250-μL French straws and sealed with a heated haemostat. The straws were then placed in a cryochamber. A computer-controlled rate freezer (CL 3300) and programmable Cryogenesis, version 4 were used to regulate the freezing rate. The sperm samples were frozen at a rate of 10°C min−1 from 4 to −80°C and then evaluated after 72 h. Of the three extenders used with each cryoprotectant, C-F HBSS had the highest fertilization rate of 75% (93% of control). This was not significantly different from the control treatment (fresh sperm) when tested with DMSO as the cryoprotectant. The lowest fertilization rate of 27% (38% of control) was resulting from the combination of 15% glycerol and C-F HBSS. This study found that fertilization, motility and viability rates in all of the experiments had a positive significant correlation (< 0.001).