Determining the sex of Trochus niloticus for induced spawning is extremely difficult. A quick and simple method for therefore developed through a process involving cutting a ‘window’ in the shell until the nacre layer was revealed. Through the window, the color of the gonad could be seen and the sex of the animal determined — dark green in the case of a female and creamy white in the case of a male. The method did not appear to inflict obvious stress nor mortality on the treated animals. Successful spawning inductions were achieved by using this method of determining the sex of the broodstock.