Cryodamages occur during sperm cryopreservation. Cryopreservation of fish sperm usually results in marked decrease in sperm quality, such as swelling or disruption of the plasma membrane, mitochondrial dysfunction, diminished sperm motility, impaired velocity, shorter motility period, denaturation, and release of some enzymes from spermatozoa. In this paper, damages in morphology, physiology,biochemistry and metabolism, and genetic integrity of fish semen after cryopreservation are discussed.New approaches in assessment of fish thawed sperm quality such as computer assisted sperm analysis,flow cytometic analysis combined with fluorescent probes and single cell gel electrophoresis are also briefly reviewed.