Goodeidae
Encyclopedia
Splitfins, are a family, Goodeidae, of teleost fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 endemic to Mexico
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 some areas of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. This family contains 40 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 within 18 genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. The family is named after ichthyologist George Brown Goode
George Brown Goode
George Brown Goode , was an ichthyologist, although most of his time was spent as a museum administrator and he was very interested in the history of science, especially the history of the development of science in America. Goode graduated from Wesleyan University and studied at Harvard University...

.

Range and Geographic Distribution

The family is divided into two subfamilies, the Goodeinae
Goodeinae
Goodeinae is a taxon of splitfins. It is a small fish which mostly lives in fresh water in Mexico, especially around Mesa Central, west of Mexico City. It is also found in brackish water on both the east and west coasts....

 and the Empetrichthyinae. The Goodeinae are endemic to shallow freshwater habitats in Mexico
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...

, particularly along the Mesa Central area, west of Mexico City
Mexico City
Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

, with some species found in brackish fringes at both the Atlantic and Pacific coasts. There are 36 species of Goodeinae in 16 genera. The Empetrichthyinae are typically found in the southwestern Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...

 of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and contains 4 species in two genera.

Physical Information

The name "Splitfins" comes from the fact that, in the male fish, the anterior rays of the anal fin are partly separated from rest of the fin. Splitfins can be up to 20 cm in length, though most species are much smaller, around 5 cm. Goodeid fish have internal fertilisation, with males positioning themselves with a flexible part of the front anal fin, separated by a notch, which makes up the andropodium. Embryos hatch out of the egg within the womb, and possess trophotaenia, a ribbon-like structure unique to Goodeids, positioned in front of the anal fin on the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 surface of the juvenile. These allow the absorption of nutrients within the womb (matrotrophy
Matrotrophy
Matrotrophy is a form of development in which the embryo is supplied with additional nutrition from the mother . This can be contrasted with lecithotrophy, in which the only source of nutrition for the embryo is yolk originally contained within its egg.In plant sciences, matrotrophy is considered...

), and are shed by juveniles shortly after birth. Female Goodeids do not store sperm, and so a copulation event must precede each pregnancy.

Conservation status

In recent years there has been a significant reduction in the range and size of Goodeid populations in this region, mainly due to anthropogenic disturbances, such as pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

, eutrophication
Eutrophication
Eutrophication or more precisely hypertrophication, is the movement of a body of water′s trophic status in the direction of increasing plant biomass, by the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage, to an aquatic system...

, habitat modification and desiccation
Desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...

; recent estimates put habitat loss at 80% compared to historic ranges. The low economic importance of Goodeid fish to Mexican fisheries and industry has led to this family being largely ignored by conservation efforts, but their small size and the dedication of a small number of aquaria hobbyists has led to a recent increase in the amount of research dedicated to the family. These investigations have highlighted the implications for conservation efforts concerning other global freshwater ichthyofauna.

Several species are threatened or extinct according to the IUCN and the U.S. Fish and Wildlife Service:
  • Vulnerable - Bold characodon
    Bold characodon
    The bold characodon is a species of fish in the Goodeidae family that is endemic to Mexico.-References:* Contreras-Balderas, S. & Almada-Villela, P. 1996. . Retrieved 3 August 2007....

    , Darkedged splitfin, Goodea gracilis
    Goodea gracilis
    Goodea gracilis is a species of fish in the Goodeidae family. It is endemic to Mexico.-Source:* Contreras-Balderas, S. & Almada-Villela, P. 1996. . Downloaded on 4 August 2007....

    , Allotoca dugesii
  • Endangered - Bluetail splitfin, Rainbow characodon, Relict splitfin
    Relict splitfin
    The relict splitfin is a species of fish in the Goodeidae family. It is endemic to the Pánuco River system in Mexico. It feeds on algae.-References:...

    , Tequila splitfin, Allotoca diazi, Manse Spring killifish
  • Critically Endangered - Blackspot allotoca, Chapultepec splitfin, Highland splitfin, Balsas splitfin
  • Extinct in the Wild - Butterfly splitfin, Golden skiffia
  • Extinct - Ash Meadows killifish
    Ash Meadows killifish
    The Ash Meadows killifish was first documented by Gilbert and historically occupied numerous springs near Ash Meadows, Nye County, Nevada...

    , Parras characodon
    Parras characodon
    The parras characodon was a species of fish in the Goodeidae family. It was endemic to Mexico.-Source:* World Conservation Monitoring Centre 1996. . Downloaded on 3 August 2007....

    , Raycraft poolfish, Pahrump Ranch poolfish

Life Cycle and Evolution

The majority of Goodeid fish are viviparous, typically giving birth to live young. The family includes a number of popular aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

 fish, for example the redtail splitfin
Redtail splitfin
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 a livebearer. However, the goodeid mating system differs in several ways from the more common livebearing fish from...

 Xenotoca eiseni. Recent phylogenetic studies have put the age of this family at approximately 16.5 million years, with the majority of divergence occurring in the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 period. The speciosity of this family can be attributed to historical volcanic and geological disturbance in this region, which created suitable conditions for allopatric speciation
Allopatric speciation
Allopatric speciation or geographic speciation is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration...

 of the fish.

Species

The Goodeidae contain around 45 living (and some recently extinct) species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in about 20 genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 and 2 subfamilies:

Subfamily Empetrichthyinae – springfishes and poolfishes
  • Crenichthys
    Crenichthys
    Crenichthys, or the springfish, is a genus of goodeid fish consisting of two species endemic to Nevada, United States, where small populations are found in isolated warm springs....

    – springfishes (2 species)
  • Empetrichthys – poolfishes (1 living species, 1 recently extinct)
    • Empetrichthys latos
      Empetrichthys latos
      Empetrichthys latos is a rare species of fish in the family Goodeidae, the splitfins. It is known by the common names Pahrump poolfish and Pahrump killifish, the former being more correct today. It is endemic to Nevada in the United States, where it was limited to the Pahrump Valley near the...

      Miller, 1948
      • Empetrichthys latos concavus – Raycraft Poolfish, Raycraft Ranch Killifish (extinct: mid-late 20th century)

    • Empetrichthys merriami – Ash Meadows Poolfish, Ash Meadows Killifish (extinct: early 1950s)


Subfamily Goodeinae
Goodeinae
Goodeinae is a taxon of splitfins. It is a small fish which mostly lives in fresh water in Mexico, especially around Mesa Central, west of Mexico City. It is also found in brackish water on both the east and west coasts....

– typical goodeids and splitfins
  • Allodontichthys (4 species)

  • Alloophorus – Bulldog Goodeid (monotypic
    Monotypic
    In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

    )
  • Allotoca
    Allotoca
    Allotoca is a genus of freshwater fish native to central Mexico. It contains the "typical" allotocas, as opposed to the Balsas Allotoca in its monotypic genus.Species:...

    – typical allotocas (8 species)
  • Ameca
    Ameca splendens
    Ameca splendens, a bony fish from the monotypic genus Amecaof the splitfin family , is commonly known as the Butterfly Goodeid or Butterfly Splitfin. It was formerly found throughout the Ameca River drainage in Mexico; the type locality is Rio Teuchitlán in the vicinity of Teuchitlán, Jalisco...

    – Butterfly Splitfin, Butterfly Goodeid (monotypic)
  • Ataeniobius – Striped Goodeid, Bluetail Goodea (monotypic)
  • Chapalichthys (2-3 species)

  • Characodon
    Characodon
    Characodon is a genus of fish in the Goodeidae family.It contains the following species:* bold characodon * parras characodon * rainbow goodeid...

    – characodons (2 living species, 1 recently extinct)
  • Girardinichthys
    Girardinichthys
    Girardinichthys is a ray-finned fish genus in the splitfin family .It contains the following species:* Girardinichthys multiradiatus – Dark-edged Splitfin, Golden Sailfin Goodeid...

    (2 species)
  • Goodea
    Goodea
    Goodea is a genus of fish in the Goodeidae family.It contains the following species:* Goodea atripinnis – Blackfin Goodea Jordan, 1880* Goodea gracilis...

    (2 species)
  • Hubbsina
    Hubbsina
    Hubbsina is a ray-finned fish genus in the splitfin family . Some authors include it in Girardinichthys as a subgenus.It contains the following species:* Hubbsina ireneae...

    (2 species, sometimes included in Girardinichthys)
  • Ilyodon
    Ilyodon
    Ilyodon is a genus of fish in the Goodeidae family.It contains the following species:* Ilyodon cortesae Paulo-Maya & Trujillo-Jiménez, 2000 – Freckled Splitfin* Ilyodon furcidens Jordan & Gilbert, 1882 – Goldbreast Splitfin...

    (3-5 species)
  • Neoophorus – Balsas Goodeid (monotypic)

  • Neotoca – Balsas Allotoca (monotypic)

  • Skiffia
    Skiffia
    Skiffia is a genus of goodeid fish that contains four species, endemic to the Mesa Central area of Mexico.They typically have a limited tolerance to environmental degradation, and so are susceptible to anthropogenic disturbance...

    – skiffias (4 species, one extinct in the wild)
  • Xenoophorus – Relict Splitfin (monotypic)
  • Xenotaenia – Leopard Splitfin (monotypic)

  • Xenotoca
    Xenotoca
    Xenotoca is a genus of fish within the goodeid family, Goodeidae. They belong to the subfamily Goodeinae. Like all members of this subfamily, they are livebearers. However, the goodeid method of mating is somewhat different from more common livebearers, such as guppies and swordtails...

    (3 species)
  • Zoogoneticus (2 species)
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