Evaluating the suitability of cryopreservation solutions for common carp (Cyprinus carpio) embryos stored at -2 °C

In the present study, cryopreservation of common carp (Cyprinus carpio) embryos was studied using a stepwise cooling protocol. Embryos at heartbeat stage were selected, placed in 15- ml plastic tubes and stored at -2 °C for 1, 7, 14, and 21 days in 2 different cryopreservation solutions: S1 (methanol + dimethyl sulfoxide + sucrose) and S2 (methanol + propylene glycol + sucrose). Embryo viability was assessed by survival rate, counting live larvae and number of failed eggs under a stereomicroscope.  The results showed that storage of common carp embryos was possible for up to 7 days at -2 °C, while the survival did not occur when storage period were 14 and 21 days. The combination of methanol with propylene glycol (S2) gave higher survival rate after 1 and 7 days stored at -2 °C. Further studies are needed in order to extend the storage time and to improve the survival rate for this species.