A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most organisms that create their offspring using sexual reproduction have two common sexes and a few less common intersex variations.
Xiphophorus is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order Cyprinodontiformes, native to Mexico and northern Central America. Xiphophorus species can be divided into 3 groups based on their evolutionary relationships: platyfish, northern swordtails, and southern swordtails. Platyfish formerly were classified in another genus, Platypoecilus, which is now obsolete. The type species is X. hellerii, the green swordtail. Like most other new world Poeciliids, platies and swordtails are live-bearers that use internal fertilization and give birth to live young instead of laying eggs like the bulk of the world's fishes. The name Xiphophorus derives from the Greek words ξίφος (dagger) and φόρος (bearer), referring to the gonopodium on the males. All are relatively small fishes, which reach a maximum length of 3.5–16 cm (1.4–6.3 in) depending on the exact species involved.
The Monterrey platyfish is a species of freshwater fish in family Poecilidae. A live-bearer, it was native to a very small section of the San Juan River system in the vicinity of the city of Monterrey, Mexico. The specific name refers to the American soldier and naturalist Darius N. Couch (1822–1897) who collected the type on a self financed expedition to Mexico.
The variable platyfish, also known as variatus platy or variegated platy, is a species of freshwater fish in family Poecilidae of order Cyprinodontiformes. A livebearer, it is native to southern Tamaulipas and northern Veracruz states in northeastern Mexico. It is a popular fish in the aquarium trade due to its prolific breeding, as are hybrids with other members of its genus, most notably the southern platyfish.
Sex chromosomes are chromosomes that carry the genes that determine the sex of an individual. The human sex chromosomes are a typical pair of mammal allosomes. They differ from autosomes in form, size, and behavior. Whereas autosomes occur in homologous pairs whose members have the same form in a diploid cell, members of an allosome pair may differ from one another.
The honey blue-eye is an endangered species of fish in the subfamily Pseudomugilinae. It is endemic to southeastern Queensland, Australia, where it is found in mildly acidic, often tannin-stained, ponds and streams in wallum habitat.
The yellow swordtail is a species of freshwater fish in the family Poeciliidae. It is endemic to the upper Coatzacoalcos River basin in southern Mexico. It is typically found in brooks and streams with slow current; it is less frequent in areas with strong current. The yellow swordtail is considered a threatened species by Mexican authorities. It reaches up to 5.1 cm (2.0 in) in standard length.
The northern platyfish is a small, endangered species of fish in the family Poeciliidae. It is endemic to the vicinity of Cuatro Ciénegas in the Mexican state of Coahuila. It is restricted to hot-spring heated ditches and marshes of the Laguna Santa Tecla. Its native water is shallow and vegetation-choked, with very stable temperatures that generally are around 27–30 °C (81–86 °F), although captive studies show the species also can live in slightly colder water.
The marbled swordtail is a species of freshwater fish in the family Poeciliidae. It was endemic to the Rio Salado system in Coahuila, northeastern Mexico. It was restricted to springs, connected creeks and pools in waters with a pH slightly above neutral and temperatures of 16–26 °C (61–79 °F), with captive studies indicating that the optimum temperature is around 24 °C (75 °F).
The Chiapas swordtail or upland swordtail is a species of livebearing freshwater fish of family Poeciliidae, and genus Xiphophorus. It is, therefore, in the same genus as the common platy and the swordtail. The Chiapas swordtail was discovered and first described by Donn E. Rosen in 1960, along with four other species of Xiphophorus.
The green swordtail is a species of freshwater/brackish fish in family Poeciliidae of order Cyprinodontiformes. A live-bearer, it is closely related to the southern platyfish or 'platy' (X. maculatus) and can crossbreed with it. It is native to an area of North and Central America stretching from Veracruz, Mexico, to northwestern Honduras.
Neoheterandria elegans or Tiger Teddy is a small live-bearing fish within the family Poeciliidae. This is the same family that includes familiar aquarium fishes such as guppies and swordtails, although Neoheterandria elegans is not nearly as popular as an aquarium fish. The fish is found in the Truando River in Colombia. Males grow to 2.0 centimetres (0.79 in) and females grow to 2.5 centimetres (0.98 in). The front half of the fish is mostly silver but the rear has alternating gold and black vertical bars.
Platy is a common name of freshwater fish in the genus Xiphophorus that lack a "sword" at the bottom of their tails. Both species are livebearers, similar to other fish of the family Poeciliidae, such as the guppy and molly. Platies are native to the east coast of Central America and southern Mexico.
Xiphophorus nigrensis, the Panuco swordtail, is a species of fish in the family Poeciliidae that is endemic to a small part of the Pánuco River basin in Mexico.
Xiphophorus mayae is a fish in the family Poeciliidae. It is found in Central America: eastern Guatemala and western Honduras. This species has red lines on its body which extend on to the upper portion of the caudal fin, males have the lower part of the caudal fin extended into a "sword".
Xiphophorus montezumae, the Montezuma swordtail, is a livebearing freshwater fish of the order Cyprinodontiformes, family Poeciliidae, and genus Xiphophorus. It is in the same genus as the common platy and the swordtail. Xiphophorus means 'sword-bearer' in Greek.
Xiphophorus continens, also known as El Quince swordtail or short-sword platyfish, is a live-bearing freshwater fish in the family Poeciliidae. It is endemic to the Pánuco River basin in east-central Mexico. Its name comes from the Greek conto, meaning short, and Latin ensis, meaning "sword". due to the species' sword size in males.
Xiphophorus pygmaeus, the pygmy swordtail, is a poeciliid fish from northeastern Mexico. It is the smallest of the swordtails. The male's sword is barely visible and the species is often called the swordless swordtail. It is sometimes kept in home aquaria, but is a rather delicate species.
Xiphophorus milleri, the Catemaco platyfish, is a poeciliid fish endemic to Mexico's Lake Catemaco and its tributaries. As it has traits of both swordtails and platies, its discovery confirmed that these two groups should be consolidated into a single genus, Xiphophorus.
Poecilia kykesis, also known as the Usumacinta molly, Petén molly, spiketail molly, or swordtail molly, is a poeciliid fish species native to the fresh and brackish waters of Mexico, Guatemala, and Belize. It belongs to the sailfin molly clade, with males exhibiting an enlarged dorsal fin. The species has a notably controversial naming history, with the former name, Poecilia petenensis, now referring to a short-finned molly species. It is a livebearer sometimes kept in aquaria.
