Summary Cryopreservation is of interest not only for fish farming but also for the conservation and genetic improvement of resources. This technique has been well established in some freshwater fish species mainly, salmonid, sturgeons and carps, however, only in the last decade research was focused in marine fish species. The benefits of sperm cryopreservation include: (i) synchronization of gamete availability of both sexes, (ii) sperm economy; (iii) simplification of broodstock management, (iv) transport of gametes from different fish farms, and (v) germplasm storage for genetic selection programs or conservation of species. These issues would certainly benefit the aquaculture industry. The tremendous impact that biotechnology is having in aquaculture has been particularly obvious in recent years. Several species are being used as research models not only for aquaculture development applications but also for medical research. Sperm cryopreservation can give an important contribution in the germ storage of all transgenic lines. However, in all applications in fish sperm, cryopreservation needs to overcome a lack in standardization of methodologies and procedures, a correct assay of seminal quality and the development of tools to characterize cryoinjury. Many efforts have recently been made in the study of DNA using different approaches such as the comet assay (single cell gel electrophoresis), TUNEL (terminal deoxynucleotidyl transferase‐nick‐end‐labelling), SCSA (sperm chromatin structure assay) and the analysis of specific DNA sequences using RT‐PCR, since DNA damage may impair fertility or embryo development. Cryopreservation of gametes would certainly benefit from a higher concern on male improvement, basically through nutrition or selection of resistant stocks (e.g. stress resistant individuals or highly adapted to captivity) producing gametes of higher quality. There is a huge window of opportunities for improve the resistance of cells to cryopreservation through diet supplementation of certain compounds such as amino acids (taurine and hypotaurine), vitamins (Vit. E and C) and lipids or through a direct supplementation of the extender media. An equilibrium of those compounds will improve spermatozoa and seminal plasma composition protecting cells against oxidative stress (lipid peroxidation, protein oxidation, DNA fragmentation, enzyme protection) that is gaining each day more importance in cryodamage research.

This review is focused on the applications of genome cryobanking of aquatic species including freshwater and marine fish, as well as invertebrates. It also reviews the latest advances in cryobanking of model species, widely used by the scientific community worldwide, because of their applications in several fields. The state of the art of cryopreservation of different cellular types (sperm, oocytes, embryos, somatic cells and primordial germ cells or early spermatogonia) is discussed focusing on the advantages and disadvantages of each procedure according to different applications. A special review on the need of standardization of protocols has also been carried out. In summary, this comprehensive review provides information on the practical details of applications of genome cryobanking in a range of aquatic species worldwide, including the cryobanks established in Europe, USA, Brazil, Australia and New Zealand, the species and type of cells that constitute these banks and the utilization of the samples preserved. Statement of relevance This review compiles the last advances on germplasm cryobanking of freshwater and marine fish species and invertebrates, with high value for commercial aquaculture or conservation. It is reviewed the most promising cryopreservation protocols for different cell types, embryos and larvae that could be applied in programs for genetic improvement, broodstock management or conservation of stocks to guarantee culture production.

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