Cryopreservation of gamete is widely used in artificial insemination of cattle, horse, pig, sheep and poultry, and has resulted in upgrading the genetic potentials of native stocks. Similarly, cryopreservation of gamete can be potentially applied in fish breeding and aquaculture. Cryopreservation of gamete is an effective way to preserve the gene pool of cultured species and to conserve the biodiversity. Given that many fish species are now threatened or endangered, it is imperative to establish a regional fish germplasm repository to preserve the vanishing genetic materials as well as to conserve the existing gene pool. Cryopreservation appears one of the most effective ways to preserve the existing gene pool; however, preservation of fish ova has not been possible yet. On the other hand, domestication of a species over many generations normally results in changes in genetic materials. Cryopreservation of spermatozoa can be used as a very effective tool for conserving the genetic materials and to prevent gene introgression. This book summarizes the methodological aspects of cryopreservation and its application in conserving the gene pool of commercial carp, silver carp.