An effective sex switch was induced in the commercially valuable red claw crayfish Cherax quadricarinatus by silencing the masculinising insulin-like androgenic gland hormone (IAG) in intersex C. quadricarinatus, which are genotypically females but functionally males. Silencing arrested spermatogenesis parallel to the onset of vitellogenesis in the previously inactive ovaries. Bioinformatic analysis confirmed successful IAG knockdown as well as the differential expression of 91 unidentified genes within the testis and androgenic gland, hypothesized to be involved in the neuroendocrine axis. The key role that IAG plays in this axis will be further explored in future by silencing IAG in genetic males and identifying the unknown genes. From this research, we aim to generate all-male populations, as has been successful in the giant freshwater prawn Macrobrachium rosenbergii. This would be valuable to the aquaculture industry as male C. quadricarinatus are more attractive, having a higher somatic growth rate and possessing the eponymous red claw. Mono-sex populations also have wider applications as a means of invasive species control, preventing the further spread of C. quadricarinatus through Australian catchments as well as a potential biocontrol agent for vector-borne parasitic diseases such as schistosomiasis.