Identification of male-specific DNA markers and generation of genetically all-female offspring using natural pseudomales in Amur catfish (Silurus asotus)

Amur catfish (Silurus asotus) is an economically important species. It demonstrates sexual dimorphism in growth, the females grow faster than the males. Therefore, production of all-female fries for Amur catfish has high commercial potential. However, sex-specific molecular markers are not available for Amur catfish, which hinders the attempt to breed and apply all-female seed for this species. In this study, we established 3 male-specific markers for Amur catfish by restriction-site associated DNA sequencing (RAD-seq) and revealed that Amur catfish has a male heterogametic (XX female, XY male) sex-determination system. Spontaneous pseudomales (individuals that are physiological male and genetic female) were identified from the wild populations of Amur catfish. Genetically all-female larvae for Amur catfish were obtained by crossing the spontaneous pseudomales with the normal females. The male-specific markers for Amur catfish are valuable tools for detecting the genetic sex of the brood fish. Furthermore, generating all-female offspring using natural pseudomales can considerably save the breeding time, which offers a new option for commercial Amur catfish seed production.