Hundreds of fish can change sex, but only now have we discovered exactly how at least one makes this change Source: https://www.newscientist.com/article/2209254-bluehead-wrasse-fish-switch-from-female-to-male-in-just-20-days/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home…