Cryopreservation of spermatozoa from rainbow trout, common carp, and marine puffer

The fertilizing capacity, motility, and associated morphological changes of rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio and marine puffer Fugu niphobles spermatozoa were studied after freeze-thaw. Freeze-thaw spermatozoa underwent an evident efflux of potassium and influx of sodium ions. The fertilizing capacity of the spermatozoa of rainbow trout and common carp decreased significantly, and the proportion of motile spermatozoa also decreased. Electron microscopy indicated obvious structural damage, especially in the trout spermatozoa. The fertilizing capacity of marine puffer spermatozoa hardly decreased after freeze-thaw. There may be a pronounced species-specificity in the requirements of the extender, the freezing and thawing method, and the freeze-thaw tolerance of fish spermatozoa.