Contrary to many reports, including a number of scientific papers, this species breeds in the same way as other cyprinodontids and does not dig pits or exhibit extended parental care.

It’s a fractional spawner with females depositing eggs on a more-or-less continuous basis when a warm temperature is maintained though ideally it should be permitted to breed on a seasonal basis in spring and late summer as it would in nature.

Wild swordtails are a fairly basic green colur. However the vast majority of swordtails available in the hobby today are hybrids of X.helleri with X.maculatus or X.variatus. There are a huge number of selectively-bred varieties available, including wagtail, lyretail, tuxedo, albino, neon, red, green and hi-fin.

Swordtails may undergo what appears to be a change in sex. In young fish this may simply be late development. However some adult females develop male characteristics which is thought …

Also known as the mosquito fish, least killifish or dwarf top minnow, H. formosa is the smallest known livebearing fish species, and one of the smallest overall fish species in the world. It's not often seen for sale these days, although it's quite widely available in hobbyist circles. When buying these, ensure they have been identified correctly as they're sometimes confused with the much more aggressive mosquito fish of the genus Gambusia….