Cryopreservation is a technique, which involve long-term preservation and storage of biological material at a very low temperature usually at -196 C ,the temperature of liquid nitrogen. It is based on the principle that very low temperature tranquilize or immobilize the physiological and biochemical activities of cell, thereby making it possible to keep them viable for very long period. The technology of cryopreservation of fish spermatozoa (milt) has been adopted for animal husbandary . The spermatozoa of almost all cultivable fish species has now been cryopreserved.
Cryopreservation overcomes problems of male maturing before female, allow selective breeding and stock improvement and enables the conservation. One of the emerging requirements for that can be used by breeders for evolving new strains. Most of the plant varieties that has been produced are based on the gene bank collections. Aquatic gene bank however suffers from the fact that at present it is possible to cryopreserve only the male gametes of finfishes and there in no viable technique for finfish eggs and embryos. However , the recent report on the freezing of shrimp embryos. However, the recent report on the freezing of shrimps embryos look promising. Therefore, it is essential that gene banking of cultivated and cultivable aquatic species be undertaken expeditiously.