User:Jaspergeli/Livebearer
From Wikipedia, the free encyclopedia
Live-bearing fish, often simply called livebearers, are fish that retain the eggs inside the body and give birth to live, free-swimming young. Among aquarium fish, livebearers are nearly all members of the Poeciliidae family and include guppies, mollies, sailfin mollies, platies and swordtails. The referring livebearers are particularly the members of the Poeciliinae subfamily which members are almost all live-bearing fishes.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Poecilia_reticulata_Fry_DSC04357_nevit.jpg/640px-Poecilia_reticulata_Fry_DSC04357_nevit.jpg)
The advantages of livebearing to the aquarist are that the newborn juvenile fish are larger than newly-hatched fry, have a lower chance of mortality and are easier to care for.
Although the whole family Poeciliidae is known as "livebearers", some species are egg-scattering with external fertilization. All African species are egg-layers, and all American species are live-bearers. So thus, the term "livebearer" is more applicable, particularly in the subfamily Poeciliinae (though there are still exceptions). Among the three subfamilies, Aplocheilichthyinae is restricted to Africa, Poeciliinae is primarily from the Americas (the only exception is the African Rhexipanchax), and Procatopodinae is mainly from Africa (the South American Fluviphylax and Pseudopoecilia are the only exceptions). This distribution suggests that the Poeciliidae predate the split between Africa and South America 100 million years ago and that live-bearing subsequently evolved in South America. Poeciliids colonized North America through the Antilles while they were connected 44 million years ago. Poeciliids then moved to Central America by the Aves land bridge on the Caribbean Plate. When South America connected to Central America three million years ago, some further dispersal southward occurred, but South American species did not move into Central America.
The original distribution of the family was the southeastern United States to the north of Río de la Plata, Argentina, and Africa, including Madagascar. However, due to the release of aquarium specimens and the widespread use of species of the genera Poecilia and Gambusia for mosquito control, poeciliids can today be found in all tropical and subtropical areas of the world. In addition, Poecilia and Gambusia specimens have been identified in hot springs pools as far north as Banff, Alberta.
They are highly-adaptable fishes, capable of living from freshwater to fully marine habitat. Though some are not tolerable, most of the species in the genus Poecilia can. They can even live in the polluted waterways, canals, ditches, streams, and rivers.