Occurs naturally in Brazil, Paraguay, Uruguay and Argentina with feral populations in Australia, New Zealand, Ethiopia and Malawi which were purportedly introduced for purposes of mosquito control but are now considered invasive.

Following Lucinda (2008) its natural range comprises the Lagoa dos Patos system, lower rio Uruguai, rio Tramandaí, and rio Mampituba in Rio Grande do Sul st…

Endemic to the Río Atrato drainage in Choco and Antioquia departments, northwestern Colombia, where the full extent of its range is somewhat unclear.

Type locality is ‘Río Truandó, a tributary of Lower Río Atrato, Colombia’, and it may be restricted to that system.

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….

This is an exceptionally hardy and adaptable species. It's not an especially common fish in stores, but is quite widely available in hobbyist circles. The common name arises from the row of modified, paired scales that form a keel running from the base of theto the caudal fin….

One of the most popular aquarium fish in the world, the guppy is instantly recognisable to most people. There are many aquarium bred varieties of this species available, most have elongated finnage and gaudy colouration. The wild form is seldom seen for sale. Unfortunately many commercially bred guppies are not very hardy due to inbreeding and over-production and are prone to disease and premature death. We therefore recommend the purchase of quality stock from breeders or society auctions.
P. …