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 -196ºC (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 28ºC. After thawing, the embryos were incubated in the aquaria at 28ºC temperature. The result showed that the cryopreservation of gastrula-staged embryo at temperatures of -4 and -196ºC affects damage and hatching percentages of African catfish embryos. The percentage of catfish embryo damage increases with the length of preservation at temperature of -4ºC 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 -196ºC 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 -196ºC.