The vast majority of fish species fertilize their eggs after they are laid.The Phallostethus cuulong – the scientific name of the fish – has become the 22nd member of the Phallostethidae family, a group of small, slender and nearly transparent surface-swimming fish that live in the waters of southeast Asi. The new species was first discovered near the Mekong River in July 2009 by Japanese scientist Koichi Shibukawa. He managed to catch it in a net, and began researching it alongside colleagues from Vietnam’s Can Tho University. The discovery of a ‘penis-headed’ fish came less than a month after a biologist in the Amazon uncovered a species of extremely rare caecilian – a legless amphibian – that was also shockingly phallic in shape.