Performance evaluation of XY all-male hybrids derived from XX female Channa argus and YY super-males Channa maculate

Snakeheads are economically important freshwater fish in China, of which males grow much faster than females, and the individual size determines the trading price. All-male NBS (northern snakehead (Channa argus, NS) ♀ × blotched snakehead (Channa maculata, BS) ♂) were produced by combining sex control, sex-specific molecular marker and hybridization of YY super-male BS and normal XX female NS. In this study, the culture performance of all-male NBS was evaluated, including yield, survival rate, growth rate, sex ratio, size uniformity, feed conversion ratio, and low-temperature resistance. The results showed that all-male NBS exhibited superior productivity traits compared to the existing cultured snakehead varieties. The average body weight of all-male NBS was heavier than that of mixed-sex NBS by 23.1–38.8 %, or inbred NS by 16.8–34.0 %; the average daily gains of all-male NBS were faster than those of mixed-sex NBS by 28.4–39.3 %, or inbred NS by 18.6–34.1 %. The male ratio of all-male NBS was more than 93.0 %, and there was a small proportion of female or bisexual individuals. The rates of body weight above 1 kg of all-male NBS were 91.3–96.4 %, which were far higher than those of mixed-sex NBS or inbred NS, which were only 62.0–75.8 %. Therefore, all-male NBS individuals are larger and more uniform. The feed conversion ratios of all-male NBS decreased 12.5–17.6 % compared to mixed-sex NBS fed artificial compound feed and 72.3 % compared to inbred NS fed iced fresh fish. In addition, the low-temperature resistance of all-male NBS was high, with only 4.1 % mortality vs. 28.5–37.4 % in other hybrids. In snakeheads trading, large individuals are more favored, and the price of snakeheads above 1 kg is approximately 40 % higher than that of individuals in the range of 0.5–2 kg. Therefore, the large and uniform all-male NBS population could bring tremendous economic benefits, because input costs are falling, while output profits are increasing. The large and uniform all-male NBS population is thus quite promising in snakeheads market applications.