The previous studies had indicated that the distant crossing between red crucian carp(Carassius auratus red var.)and common carp(Cyprinus carpio L.)results in chromosomal double in germ cells. In order to explore the potential ability of polyploidization in the goldfish from close crossing,by observing the chromosomal spreads of germ cells in testis,combining the flow cytometer examined DNA content of sperms,we studied the chromosomal characterization of spermiogenesis and the ploidy of sperms in goldfish.The results showed that the majority of spermatocytes in goldfish had normal chromosomal behavior in meiosisⅠ,like chromosome pairing with 50 bivalents.Furthermore,the bivalent number of a part of germ cells in goldfish doubled obviously among 17.0% of all examined chromosomal spreads,the doubling showed 100,150,200,250,300 and even more bivalents,which is similar to the chromosomal number doubling in distant crossing between red crucian carp and common carp. Unlike distant crossing species,the goldfish stably produced haploid sperms though.Taken together,it was concluded that both close crossing and distant crossing lead to chromosome doubling in germ cell.However,the production of functional gametes in process of chromosome doubling depends mainly on the genetic relationship between the parents.