Zoogoneticus tequila, Tequila splitfin or simply Tequila fish, is a species of goodeid fish (family Goodeidae) from Mexico. [1] [2] [3] Viviparous topminnows make up 36 of the species within it this family. Z. tequila, one of these 36 species, has a very limited population endemic to Mexico. [4] The specific epithet, tequila, derives from the Tequila Volcano, which looms near the type locality. [5]
Zoogoneticus tequila is endemic to the Ameca River basin in west-central Mexico. Its current distribution is restricted to a single spring pool in Teuchitlán, only 4 metres (13 ft) in diameter, where a population consisting of less than 50 adult fish found in the early 2000s. [6] Before the discovery of the pool population in 2000/2001, Z. tequila was generally thought to inhabit rivers; However, no fish could be found in the original habitat and the species was considered extinct in the wild. [7] Introduced fish species have been implicated in the disappearance of Z. tequila from its type locality. [6] [7]
The small pool where the endemic population of Z. tequila currently inhabits is made of mostly mud and silt, along with rocks, sand, and minimal vegetation. The fish are primarily found in more shallow depths within the pool, preferring warmer temperatures. [8] After reintroduction efforts for seven years, the Z. tequila population has recovered and now flourishes in its endemic location. [9] The Ameca River Basin is home to many endemic species that fall within the Goodeidae family, but like Z. tequila, most remain outnumbered by introduced species such as the guppy. [7] [10] With such a small population of minimal juveniles and a few adults, Z. tequila was particularly threatened by inbreeding and poor genetic variation, ultimately facing the threat of extinction before any reintroduction efforts were made. [4] Additionally, introduced species that drive competition up to a nearly impossible level for this fish is another factor attributed to the initial population decline.
Along with other Mexican goodeids, Zoogoneticus tequila are viviparous; this led the genus to be originally included in family Poeciliidae. [11] The clutch size is up to 29 young. [7] Males are smaller than females, with standard length up to 4.1 cm (1.6 in) in males and up to 5.8 cm (2.3 in) in females. [11] The clutch size is up to 29 young. [7] Total length can reach 7 cm (2.8 in) in females. [5] The sexes can also be distinguished by colouration. [5] Adult males have cream-colored terminal bands on the anal and dorsal fin. The caudal fin of adult males has crescent-shaped band of red-orange, orange, or yellow. This crescent-shaped tail is one of the distinguishing features that helps to separate this fish from the other species within its genus: Zoogoneticus quitzeoensis. The rest of the caudal fin is not pigmented and is transparent. Some large adult females share this caudal coloration but generally their caudal fins are transparent. Both sexes display olive shaded, mottled bodies with males typically darker than the females. Generally, adults will lose the mottled coloration in their caudal peduncle as they age. Juveniles are lighter colored with more obvious mottling. [12]
The female Z. tequila fish have a single, median ovary that is common amongst the entire Goodeidae family. During reproduction, the embryos develop in the cavity of this ovary. Females give birth to free-swimming fry after the development within the ovary cavity. [13] During each brood, females will produce 10-29 offspring, typically during the summer season, though some studies have found females to reproduce in winter in rare occurrences. Once the fry are given birth to, they are left to fend for themselves, with no parental care provided by the mother. Sexual maturity for this species is reached around 6-10 weeks of age, when the life cycle of this fish starts over again. [14]
Much of the wild diet and eating patterns of Z. tequila are inferred from congeners such as Z. quitzeoensis, which consists of amphipods, insects, ostracods, and detritus. In their existing location in the spring pool, Z. tequila fish typically eat various zooplankton and insect larvae, with chironomid larvae being most popular. [15] [16] The conical teeth that can be found on this fish imply it is a predator that hunts small invertebrates or larvae in the wild, though wild populations aren’t attainable to observe due to their extinction outside of the pool. [17] There have also been recorded instances of cannibalism of the immature young. [18]
Typical predators endemic in the geographic range are Esox sp. and Thamnophis sp. [18] There are also many introduced species in the area that likely prey on or outcompeted Z. tequila such as Xiphophorus maculatus, Tilapia aurea, Lepomis macrochirus, Cyprinus carpio, X. helleri and Poecilia reticulata. [5] The singular pool that the Z. tequila is found in consists of 80% exotic species, and 50% twospot livebearers, or Pseudoxiphophorus bimaculatus. This invasive species is one of the main threats that studies have shown to decrease the population and viability of the Z. tequila. When surrounded by more native species, Z. tequila has historically shown a higher abundance than when surrounded by invasive species such as these predators. [19]
After a few successful reintroductions of Z. tequila in the wild became established, the International Union for Conservation of Nature declared this species endangered. However, it is still considered by many to be extinct in the wild. [20] DNA analysis of natural populations of Z. tequila have shown that because the populations are extremely small, there is a large amount of inbreeding which could be contributing to the precipitous decline in populations in the wild. [6] Ideally, the process to recover the Z. tequila even further would be to introduce subjects from the wild to the very limited, endemic population of the river. Since the wild population was declared extinct nearly twenty years ago, this opportunity is nonexistent. [21] Instead of using species from the wild, recent efforts by scientists beginning in 1998 have been able to replenish the declining population within the river through breeding the fish in labs. To do this, Z. tequila fish that were bred by scientists were reintroduced into the river in intervals, with 1,500 fish being released into the river in total. This project came from the collaboration of zoologists from Chester Zoo and European institutions, ultimately creating a lab with Mexican scientists to bring this species to recovery. [22]
Beyond simply reintroducing the species and allowing a larger population to reach replenishment, it is also important to consider the causes behind the endangered species to begin with. [23] Freshwater fish particularly face a large threat of extinction due to the proportionally higher rate of endemic species in these regions. It is difficult to understand the complexity of the threats since this species is not largely studied. However, the research that has been done to understand the cause of the Z. tequila going extinct in the wild largely attributes anthropogenic pollution as well as the introduction of invasive species to be the largest reasons. [8] Having an environment in which the minimal, endemic population can grow past a point where inbreeding poses a significant threat is a main driver in recent efforts.
Goodeidae is a family of teleost fish endemic to Mexico and some areas of the United States. Many species are known as splitfins. This family contains about 50 species within 18 genera. The family is named after ichthyologist George Brown Goode (1851–1896).
Skiffia is a genus of goodeid fish that contains four species, endemic to the Mesa Central area of west-central Mexico. They are restricted to the Lerma–Grande de Santiago, Ameca and Grande de Morelia river basins, including lakes Chapala, Pátzcuaro, Zirahuén and Cuitzeo. They inhabit stagnant or slow-moving waters such as lakes, ponds, channels and ditches, and prefer shallow depths.
The butterfly splitfin or butterfly goodeid is a bony fish from the monotypic genus Ameca of the splitfin family (Goodeidae). It was formerly found throughout the Ameca River drainage in Mexico; the type locality is Rio Teuchitlán in the vicinity of Teuchitlán, Jalisco. The species was only ever found in an area about 10 miles (15 km) in diameter.
The rainbow goodeid is a species of critically endangered freshwater fish in the family Goodeidae, and are endemic to Mexico. Specifically, they are found in shallow springs and ponds in the Durango and Coahuila area. They were first identified in 1866 by Albert Günther.
Allotoca is a genus of splitfins that are endemic to west-central and southwest Mexico, where restricted to the Lerna–Chapala–Grande de Santiago, Ameca and Balsas river basins, as well as various endorheic lake basins in Michoacán and Jalisco. All Allotoca species are seriously threatened.
Potosi pupfish is a species of fish in the family Cyprinodontidae. It is endemic to Mexico, but is now extinct in the wild, only surviving in captivity.
The dark-edged splitfin is a species of fish in the family Goodeidae endemic to Mexico. It is a live-bearing, cold-water fish from the mountains of Mexico. The species is incredibly temperature sensitive. If water is too cold, all offspring turn out to be male. If water is too hot, females will birth their first brood of only 1–3 fry and then die shortly thereafter, which makes it very difficult to maintain a colony. It is also a primarily carnivorous species that eats a variety of insects. Girardinichtys multiradiatus is an endangered species with multiple population threats with little conservation efforts put in place to protect the species.
Girardinichthys is a genus of splitfins that are endemic to Mexico. These highly threatened fish are native to the upper Lerma and Balsas basins, as well as water systems in the Valley of Mexico. Through man-made channels G. viviparus has been able to spread to the upper Pánuco River basin. These small fish reach up to 6.5 cm (2.6 in) in length. The name of this genus honours the American herpetologist and ichthyologist Charles Girard (1822-1895).
Goodea is a genus of splitfins that are endemic to Mexico. They are found in a wide range of habitats in several river basins that originate in the Central Plateau, such as Pánuco, Lerma–Chapala–Grande de Santiago and Balsas. Overall this genus is among the most widespread and successful splitfins, although they also have declined and the relatively restricted G. gracilis is considered vulnerable by the IUCN. This genus includes the largests splitfins, reaching a standard length of up to 20 cm (8 in). They are primarily herbivores, but also take small organisms like tiny crustaceans and snails. The is named in honour of the American ichthyologist George Brown Goode (1851-1896).
The Ameca River is a river of some 230 km (140 mi) in length in western Mexico. It originates in the Bosque de la Primavera in Jalisco, 23 km to the west of state capital Guadalajara; flows through the city of Ameca; and then forms the boundary between Jalisco and Nayarit on its way to the Pacific Ocean, where it drains into the Bahía de Banderas at Puerto Vallarta, Jalisco. Its main tributaries are the Ahuacatlán and Amatlán de Cañas.
Xenotoca is a genus of fish in the family Goodeidae from Mexico, where various species are found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma–Grande de Santiago, Panuco, Cuitzeo and other basins of the Mesa Central. While no goodeid is a very common aquarium fish, the redtail splitfin, is one of the most common aquarium goodeids; its bright colors offset its reputation for being aggressive towards and occasionally even killing tankmates. Similarly to X. eiseni, two species described in 2016 have males with red-orange tails, but this feature is not shared by the remaining members of the genus. All Xenotoca species are relatively small, reaching up to 9 cm (4 in) in standard length.
The redtail splitfin or redtail goodeid is a species of goodeid fish from the family Goodeidae and subfamily Goodeinae. Like other members of Goodeinae, the redtail splitfin is native to Mexico and a livebearer. However, the goodeid mating system differs in several ways from the more common livebearing fish from the family Poeciliidae that includes guppies and swordtails. While no goodeid species is a very popular aquarium fish, the redtail splitfin is one of the most popular. Only the male has the red-orange tail for which it is named. Its specific name honours the collector of the type, Gustav Eisen (1847–1940) who was Curator of Marine Invertebrates at the California Academy of Sciences in San Francisco, California.
Goodeinae is a subfamily of splitfins from Mexico, part of the family Goodeidae. They are small fish which mostly live in fresh water, especially around Mesa Central, west of Mexico City. Members of the subfamily are also found in brackish water on both the east and west coasts. They typically have small ranges and many are seriously threatened. The subfamily takes its name from its type genus Goodea and so is ultimately named after the American ichthyologist George Brown Goode (1851-1896).
The Ameca shiner is a species of cyprinid fish in the family Cyprinidae. The Ameca shiner was described in 1986 from upper parts of the Ameca River drainage in Jalisco, Mexico. Although already feared extinct by 1969, and listed as such by the IUCN when rated in 1996, a tiny population was rediscovered in 2001. Some were brought into captivity to form the basis of a breeding program. These have been used for a reintroduction project since 2015.
Empetrichthys is a genus of splitfins endemic to the state of Nevada in the United States. In 1989 they only had an estimated population of 24800, while its two other subspecies had gone extinct. This species mating season typically falls in spring. These animals are in danger and facing threats because their water is drying out because of pumping of ground water for agricultural developments.
Zoogoneticus is a genus of splitfins that are endemic to the Lerma–Chapala–Grande de Santiago, Armería, Ameca, Cuitzeo and Zacapu basins in west-central Mexico. They inhabit lakes, streams, ponds, canals and ditches, and prefer shallow waters with no or only a moderate current. They are predators that feed on small invertebrates. Zoogoneticus are fairly small fish, reaching up to 8 cm (3 in) in total length.
Skiffia francesae, the golden skiffia or tiro dorado, is a species of splitfin endemic to the Rio Teuchitlán, a tributary of Río Ameca in western Mexico. It is extinct in the wild, but has been maintained in aquaria and the aquarium hobbyist trade.
Allotoca goslinei, commonly known as the banded allotoca or tiro rayado in Spanish, is a species of fish in the family Goodeidae. First described in 1987, it was once endemic only to the Ameca River basin in the Mexican state of Jalisco. It is now known to be extinct in the wild.
Xenotoca doadrioi or San Marcos redtail splitfin is a bony fish species in the goodeid family. Until 2016 it was considered to be a variant of the redtail goodeid, X. eiseni, sometimes referred to as the San Marcos variant. A 2016 study by Omar Dominguez-Dominguez, et al. split the redtail goodeid into three separate species: X. eiseni, X. doadrioi and X. lyonsi.
Xenotoca lyonsi, the Tamazula redtail splitfin, is a bony fish species in the goodeid family. Until 2016 it was considered to be a variant of the redtail goodeid, X. eiseni. A 2016 study by Omar Dominguez-Dominguez, et al. split the redtail goodeid into three separate species: X. eiseni, X. doadrioi and X. lyonsi.