Performance evaluation of the new all-male hybrid snakehead produced by XX♀ Channa maculata × YY♂ Channa argus

Snakeheads are economically important freshwater fish in China and exhibit pronounced sexual dimorphism, with males substantially outperforming females in growth. In our previous study, YY super-males (YY♂) of northern snakehead ( Channa argus , NS) was generated through estrogen-induced sex reversal combined with sex-specific molecular markers. Here, we produced all-male BNS by crossing normal XX female (XX♀) blotched snakehead ( C. maculata , BS) with YY♂ NS, integrating hybridization with sex control technologies. We systematically compared all-male BNS against inbred parental lines (BS and NS), mixed-sex BNS, and all-male NBS (NS♀ × BS♂) across diverse settings, including net cage trials, communal pond rearing, multi-location field evaluations, and large-scale commercial demonstrations. All-male BNS consistently outperformed all control groups. Relative to mixed-sex BNS, it exhibited 35.82∼41.97% faster growth, 19.40∼22.44% lower feed conversion ratio, higher proportions of fish exceeding 1 kg (90∼100% vs. 50∼74%), and superior size uniformity (weight coefficient of variation: 10.24∼10.97% vs. 25.11∼31.48%). Compared to all-male NBS, it demonstrated an 11.01∼12.49% growth advantage and 2.88∼3.85% better feed efficiency, likely attributable to directional maternal effects, though the precise molecular mechanisms require further investigation. High survival (91.08∼97.34%) and male sex ratios (95∼100%) further support its commercial viability. Although low-frequency (0∼5%) intersex individuals were observed, they did not compromise population-level productivity. Validated through extensive field trials and commercial demonstrations, all-male BNS exhibits highly consistent growth potential and production stability and significant advancement for aquaculture, particularly in high-temperature regions of southern China. By combining the feed efficiency of BS with the growth potential of NS while capitalizing on male growth superiority, all-male BNS offers a commercially superior product and provides a scientific foundation for genetic improvement programs in other species. Future research should elucidate the molecular basis of the rare intersex phenotype.