Potential and Advantage of Goldfish as Surrogate Host for Generating Grass Carp Gametes

Grass carp (Ctenopharyngodon idellus) is a significant species in aquaculture across Asia, accounting for approximately 10% of global freshwater aquaculture production. Nevertheless, advancements in breeding have been substantially hindered by the species' extended sexual maturation period of 4–5 years. Germline stem cell transplantation (GSCT) presents a potential technology to accelerate fish breeding by shortening the generation interval through the use of recipient with shorter sexual maturation period. In this study, smaller-bodied goldfish recipients (Carassius auratus) characterized by shorter generation time, high fecundity, and scalable year-round gamete output were employed for the production of grass carp gametes. Donor testicular cells isolated from the testes of 1.5-year-old grass carp were intraperitoneally transplanted into 3–4 days post-hatching germ cell-depleted goldfish larvae generated by knocking down dnd gene. At 6 months post transplantation, 11 out of 21 male goldfish recipients successfully produced functional donor-derived grass carp sperm, with an average milt volume of 754 μL. Compared with recipient sterile zebrafish, which lacked ovary formation, donor spermatogonia stem cells from grass carp differentiated into oogonia stem cells and further developed into late vitellogenic oocytes within the goldfish's gonadal somatic cells. These findings position goldfish as a promising alternative recipient for grass carp GSCT and provide a scalable platform for donor-derived sperm production, with future potential for generating both male and female grass carp gametes.