We focused on freezing of common carp sperm
utilizing a practical and inexpensive protocol for aquaculture. Sperm were diluted 1:1 in
one of six extenders (common carp sperm extenders; CCSE 1–CCSE 6) containing three
types of cryoprotectants (dimethyl sulfoxide; DMSO, methanol; MET and propylene glycol;
PG) at a final concentration of 10%, and frozen at a rate of 10 ◦C/min from an initial
temperature 25 to −40 ◦C before storage in liquid nitrogen.