Study on the biological characteristics of a new germplasm of grass carp (gynogenetic grass carp ♀ × gold grass carp ♂)

This study developed a novel grass carp variety, designated improved grass carp (IGC), by crossing gynogenetic grass carp (GGC, 2n = 48) females with gold grass carp ( Ctenopharyngodon idella red var., RGC, 2n = 48) males, aiming to integrate desirable parental traits and generate new hybrid germplasm. Using common grass carp ( Ctenopharyngodon idella , GC, 2n = 48) as a control, we systematically compared the muscle nutritional composition and genomic structural characteristics among RGC, IGC, and GC. The external morphology of IGC closely resembled that of GC, with no significant differences (P > 0.05) in meristic traits or morphometric ratios across the three groups. Flow cytometry and chromosome preparation confirmed that IGC is diploid (2n = 48), and its DNA content did not differ significantly from that of GC (P > 0.05), indicating favorable genetic stability. Muscle nutritional analysis revealed that IGC exhibited the highest contents of crude protein, crude fat, and ash among the three groups. Regarding fatty acid profiles, IGC showed 24.4%, 36.3%, and 43.7% higher contents of total fatty acids, polyunsaturated fatty acids (PUFA), and highly unsaturated fatty acids (EPA + DHA), respectively, compared with GC, demonstrating a substantial improvement in fatty acid nutritional quality. In summary, this study successfully confirms the superior muscle fatty acid quality of IGC and enriches both the theoretical framework and germplasm resources for intraspecific hybridization breeding in grass carp.