Ultra-fast genetic recovery of dead fish through cross-family germline stem cell transplantation

The conservation of genetic resources from aquaculture species and endangered fish is increasingly challenged by large body size, long reproductive cycles, and limited opportunities for timely intervention after death. Here, we establish and validate an ultra-fast genetic platform based on germline stem cell transplantation to enable postmortem genetic recovery in fish. Using grass carp (Ctenopharyngodon idella) as a representative warm-water species, we systematically quantified the relationships among postmortem tissue freshness, germline stem cell viability, and transplantation efficiency, and demonstrated that low-temperature preservation plays a decisive role in maintaining germline activity after death. Germline stem cells isolated from deceased grass carp were transplanted into germ-cell–depleted zebrafish recipients, where they rapidly colonized recipient gonads, underwent proliferation and differentiation, and generated functional donor-derived gametes within three months. These gametes supported successful fertilization and normal embryonic development, ultimately yielding viable grass carp offspring. Our results reveal an intrinsic postmortem resilience of germline stem cells and demonstrate that cross-species transplantation into small, fast-maturing hosts can dramatically accelerate genetic recovery. This strategy overcomes key biological and logistical constraints associated with conventional breeding-based rescue approaches and provides a rapid, scalable, and broadly applicable framework for postmortem genetic resource conservation in aquaculture and endangered fish species.