This invention is directed to methods for manipulating sex, reversing sex, changing sex ratio, or moderating crustacean androgenic gland peptide expression in crustaceans for producing a monosex culture. In one embodiment, the present method comprises the step of injecting a dsRNA for the gene of IAG into a male crustacean. In another embodiment, the present method comprises the step of injecting a dsRNA for the gene of IAG into a female crustacean that had acquired a spermatophore (a sperm sac) after mating with a male. In another embodiment, the present invention provides a method of producing a monosex culture of crustacean by introducing a recombinant IAG peptide into the female crustacean, thereby obtains male with altered sexual characteristics for mating with a normal female. In one embodiment, the crustacean is a shrimp or lobster.
