The zebrafish is the simplest model vertebrate amenable to genetics, and genome information and methods of embryo manipulation have been accumulated worldwide. The numbers of mutant and transgenic zebrafish strains are rapidly increasing, and these strains will play important roles in the basic biology research and as model systems of the human diseases in the future. Although researchers who had established zebrafish strains, were distributing the fish on a discretionary basis, a well-established system for distributing the strains did not exit in Japan prior to 2003. Due to these circumstances, a system to collect, preserve, and provide zebrafish strains was established as part of the National BioResource Project useful model vertebrates in Japan and to the world.