Preliminary study: The effect of cryopreservation on the gastrula-staged embryo of African catfish (Clarias gariepinus)

This study was aimed to observe the effect of cryopreservation on gastrula-staged embryo of African catfish. The gastrula-staged embryos were treated 5% (v/v) solutions concentration of dimethyl sulfoxide, propylene glycol, honey, and combined cryoprotectants, respectively and preserved at temperatures of-4 and-196°C (in liquid nitrogen) for 30 min, 1 h, 2 h, 3 h, 4 h, 5 h, and 6 h, respectively. Thawing of embryos was conducted in freshwater at temperature of 28°C. After thawing, the embryos were incubated in the aquaria at 28°C temperature. The result showed that the cryopreservation of gastrula-staged embryo at temperatures of-4 and-196°C affects damage and hatching percentages of African catfish embryos. The percentage of catfish embryo damage increases with the length of preservation at temperature of-4°C for all treatments. A combination of DMSO+honey and PG+honey has the lowest damage percentage and the highest hatching rate of catfish embryo compared to other treatments (p<0.05). Meanwhile, total embryo damage occurs since the first 30 min of preservation at temperature of-196°C for all treatments. Cryoprotectant toxicity and inability to protect the embryo are thought to be a cause of damage and death of catfish embryos on preservation, especially at temperature of-196°C.