**5. Conclusion**

A method has been developed for the cryopreservation of wels catfish sperm that can be used in the practice of fish farms. It is possible to fertilize 150-300 g eggs with sperm cryopreserved in large volumes (5-ml straws). The motility and hatching rate of frozen sperm correspond with the currently used routine method of fertilization with fresh sperm.

The survival and growth parameters of wels catfish larvae originating from cryopreserved sperm was investigated for the first time. According to this study it can be said that survival rate of larvae originating from cryopreserved sperm reaches and in some cases exceeds that of control larvae. This result proves the practical usage of the cryopreservation method.

Pikeperch sperm has successfully been cryopreserved for the first time, and the developed method was tested in hatchery conditions.
