Amazon molly
The Amazon molly, Poecilia formosa, is a freshwater fish which reproduces through gynogenesis. This means although females must mate with a male, genetic material from the male is not incorporated into the already diploid egg cells the mother is carrying (except in extraordinary circumstances), resulting in clones of the mother being produced en masse. This characteristic has led to the Amazon molly becoming an all-female species. The common name acknowledges this trait as a reference to the Amazon warriors
The Amazons are a nation of all-female warriors in Greek mythology and Classical antiquity. Herodotus placed them in a region bordering Scythia in Sarmatia...

, a female-run society in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

. They are native to warm, fresh waters of northeastern Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 and to the extreme southern parts of the U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 state of Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 on the Rio Grande
Rio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...

 and the Nueces River
Nueces River
The Nueces River is a river in the U.S. state of Texas, approximately long. It drains a region in central and southern Texas southeastward into the Gulf of Mexico. It is the southernmost major river in Texas northeast of the Rio Grande...


In nature, the Amazon molly typically mates with a male from one of four different species, either P. latipinna
Sailfin molly
The sailfin molly, Poecilia latipinna, is a species of fish, of the genus Poecilia. They inhabit fresh, brackish, and coastal waters from North Carolina to Texas and the Yucatán Peninsula of Mexico.- Taxonomy :...

, P. mexicana, P. latipunctata, or occasionally P. sphenops
Poecilia sphenops
Poecilia sphenops is a species of fish, of the genus Poecilia, known under the common name molly; to distinguish it from its congeners, it is sometimes called short-finned molly or common molly. They inhabit fresh water streams and coastal brackish and marine waters of Mexico...

. One other male that could possibly exist in the Amazon molly's natural range that could induce parthenogenesis in Amazon molly females is the triploid Amazon molly males. These triploid males are very rare in nature and are not necessary in the reproduction of the species, which is why the species is considered to be all female.

The Amazon molly reaches sexual maturity anywhere from one to six months after birth, and typically has a brood (batch of young) between 60 and 100 fry (young) being delivered every 30–40 days. This lends itself to a large potential for population growth as long as host males are present. The wide variability in maturity dates and brood sizes is a result of genetic heritage, varying temperatures, and food availability. They will become sexually mature faster and produce larger broods in warm (approximately 80°F) water that provides an overabundance of food.
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