by joefish72 Thu Jul 28, 2011 4:44 pmLike most livebearers guppies and mollies are pretty easy to sex. The males have a gonopodium fin (penis) which is usually visible by 4 months but sometimes it could take upto 6 months to know for sure. The photo below shows a male and female Phalloceros caudimaculatus and the male has been highlighted.
