Effect of different concentrations of cryoprotectant and extender on the hatching of indian major carp embryos (Labeo rohita, catla catla, and cirrhinus mrigala) stored at low temperature

Rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) embryos were examined for hatching success after short-term (8-13 h) storage at low temperature (4 degreesC) using three concentrations of three cryoprotectants, methanol (1, 2, and 3 M), dimethyl sulfoxide (1.282, 1.923, and 2.564 M, equal to 10, 15, and 20%), and glycerol (1.087, 1.63, and 2.174 M, equal to 10, 15, and 20%), separately as well as together with a single concentration of sucrose (0.5 M). The aim was to determine the toxicity of cryoprotectants for fish embryos at 4 degreesC. Of the cryoprotectants used, methanol was found to be most suitable for low-temperature storage in the refrigerator. The hatching rate of embryos was significantly higher when sucrose was added to methanol when compared with methanol alone. Of the three concentrations of methanol tested, survival was maximal at 2 M in the presence of 0.5 M sucrose (rohu, 57.5 +/- 5.24; catla, 47.5 +/- 5.24; and mrigal, 32. 5 +/- 5.24). Both rohu and catla embryos survived with either 1 or 2 M methanol, with or without the addition of sucrose, but the addition of sucrose was essential for survival of mrigal at 1 and 2 M methanol. Copyright 1998 Academic Press.