Blind Cave Fish aka Mexican Tetra

  • Scientific Name:Astyanax fasciatus mexicanus

    Blind Cavefish aka Mexican Tetra

  • Other Names: Mexican Tetra
  • Family: Characidae
  • Origin: Texas, Mexico, Central America to Panama
  • Adult Size: 3.5 inches (9 cm)
  • Social: Peaceful – suitable for community tank
  • Lifespan: 5+ years
  • Tank Level: Mid dweller
  • Minimum Tank Size: 20 gallons
  • Diet: Omnivore, eats most foods
  • Breeding: Egglayer
  • Care: Easy
  • pH: 6.0 – 7.8
  • Hardness: to 30 dGH
  • Temperature: 68-77 F (20-25 C)


Easily the most novel fish commonly available today, the Blind Cave fish i s named for what it lacks – eyes. Although totally devoid of eyes, they have an uncanny ability to navigate adeptly, apparently by bouncing sound waves off objects around them. Originating from deep caves in Mexico, where the lack of light and predators has made vision un-necessary.

Eyes are not the only feature this fish lacks, this unique fish is also without pigmentation, taking on a pink hue from the blood vessels beneath the skin. The lack of eyes and color have not lessened it’s popularity. Active, peaceful and easy to care for, the Blind Cave fish makes an interesting addition to a community tank.
Recently, studies have been conducted to see if eye development could be stimulated. Surprisingly, when lenses from sighted fish were transplanted to the Blind Cave fish, it began to develop an eye. It is hoped that further study of this phenomenon may prove useful in treating blindness in humans.


Water parameters are not critical for this fish, and it will tolerate a range of conditions from soft acidic to hard alkaline water. Likewise, water temperature is not critical and may range from the 60’s to the 80’s. Because they are an active swimmer, ample open space in which to swim is welcomed. Lighting is not a major concern, however it has been reported that the prefer.


Blind Cave fish are as easy to feed as they are to provide a habitat for. They will consume any food offered, including flake, freeze-dried, frozen, and live foods. For optimum health they should be fed a varied diet. When planning to spawn them, they should be conditions with feedings of fed live foods.

Females are somewhat larger and plumper than males, but otherwise have no distinguishing markings. Prior to spawning the fish should be fed live foods for several days. To stimulate spawning drop the water temperature to 66-68 degrees. The female will scatter up to one hundred eggs throughout the breeding tank.

The eggs should not be moved, as they are sensitive to handling. Fry will hatch within two to three days, and be free swimming before the week is out. Freshly hatched or frozen baby brine shrimp may be fed, as well as commercially prepared fry foods, or very finely crushed flake foods. Interestingly, the developing fry initially have eyes which atrophy as the fish matures.

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