page_title: Cavefish
section_title: Conservation
hierarchical_section_title: Cavefish / Conservation
caption_attribution_description: Deutsch&#x3a;&#32; Astyanax mexicanus, Characidae, Blinder Höhlensalmler; Staatliches Museum für Naturkunde Karlsruhe, Deutschland.English&#x3a;&#32; Astyanax mexicanus, Characidae, Blind Cave Tetra; Staatliches Museum für Naturkunde Karlsruhe, Germany.Français&#x202f;&#x3a;&#32; Un tétra aveugle (Astyanax mexicanus, Characidae) en captivité. Photo prise au Staatliches Museum für Naturkunde Karlsruhe en Allemagne.
context_page_description: Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish and hypogean fish.
  There are more than 200 scientifically described species of obligate cavefish found on all continents, except Antarctica. Although widespread as a group, many cavefish species have very small ranges and are seriously threatened. Cavefish are members of a wide range of families and do not form a monophyletic group. Typical adaptations found in cavefish are reduced eyes and pigmentation.
context_section_description: Although cavefish as a group are found throughout large parts of the world, many cavefish species have tiny ranges (often restricted to a single cave or cave system) and are seriously threatened. In 1996, more than 50 species were recognized as threatened by the IUCN and many, including several that are rare, have not been accessed at all. For example, the critically endangered Alabama cavefish is only found in the Key Cave and the entire population has been estimated at less than 100 individuals, while the critically endangered golden cave catfish only is found in the Aigamas cave in Namibia and has an estimated population of less than 400 individuals. The Haditha cavefish from Iraq and the Oaxaca cave sleeper from Mexico may already be extinct, as recent surveys have failed to find them. In some other cases, such as the Brazilian blind characid which went unrecorded by ichthyologists from 1962 to 2004, the apparent "rarity" was likely because of a lack of surveys in its range and habitat, as locals considered it relatively common until the early 1990s (more recently, this species appears to truly have declined significantly). Living in very stable environments, cavefish are likely more vulnerable to changes in the water (for example, temperature or oxygen) than fish of aboveground habitats which naturally experience greater variations. The main threats to cavefish are typically changes in the water level (mainly through water extraction or drought), habitat degradation and pollution, but in some cases introduced species and collection for the aquarium trade also present a threat. Cavefish often show little fear of humans and can sometimes be caught with the bare hands. Most cavefish lack natural predators, although larger cavefish may feed on smaller individuals, and cave-living crayfish, crabs, giant water bugs and spiders have been recorded feeding on a few species of cavefish.
  Caves in some parts of the world have been protected, which can safeguard the cavefish. In a few cases such as the Omani blind cavefish (Oman garra), zoos have initiated breeding programs as a safeguard. In contrast to the rarer species, the cave form of the Mexican tetra is easily bred in captivity and widely available to aquarists. This is the most studied cavefish species and likely also the most studied cave organism overall. As of 2006, only six other cavefish species have been bred in captivity, typically by scientists.
caption: The cave form of the Mexican tetra is easily bred in captivity and the only cavefish widely available to aquarists
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