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Silvery Mexican tetras, the surface form of the blind cavefish, swimming over plants.
Photo: Clinton & Charles Robertson, CC BY 2.0, via Wikimedia Commons

Mexican Blind Cavefish

Astyanax mexicanus

A small pale fish with no working eyes that lives in dark Mexican caves and finds its way by feeling vibrations.

🐟 Fish
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About the Mexican Blind Cavefish

Mexican blind cavefish are 3 to 5 inches long. The cave form is pale pink or white with see-through skin and no working eyes. They live in caves and sinkholes in northeastern Mexico, especially the Sierra de El Abra region. They eat insects, small crustaceans, algae and other bits of food that wash into the caves, and they can survive long periods without eating.[1]

Quick facts

Scientific name
Astyanax mexicanus[1]
Size
About 3 to 5 inches long.[1]
Weight
A few grams.[1]
Diet
Omnivore. Insects, small crustaceans, algae, plants and debris.[1]
Habitat
Underground caves and sinkholes; surface forms in rivers and streams.[1]
Where it lives
Northeastern Mexico and parts of southern Texas.[1]
Conservation status
Least Concern (IUCN Red List, assessed 2011).[2]

Fun facts

  • Cave and river forms of this fish are the same species.[1]
  • You can see some of its organs through its skin.[1]
  • It can survive a long time without food.[1]

Vocabulary

evolution
The slow change of living things over many generations.
sinkhole
A hole in the ground where rock has dissolved and collapsed.
translucent
Letting some light through, almost see-through.
pigment
A natural color in skin, hair or scales.
least concern
A conservation label meaning a species is widespread and not at risk of dying out soon.

See it in person

These zoos had this animal when we gathered our information, but animals sometimes move. Check the zoo's website or contact the zoo before you visit.

Sources

  1. [1] Toronto Zoo. “Mexican blind cavefish (Mexican tetra).” https://www.torontozoo.com/animals/Mexican%20Blind%20Cavefish%20(Mexican%20Tetra) (accessed 2026-10-02)
  2. [2] IUCN Red List of Threatened Species. “Astyanax mexicanus (Mexican Tetra).” https://www.iucnredlist.org/species/62191/3109229 (accessed 2026-10-02)

Facts last checked 2026-10-02.

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