Blind cave tetra - Astyanax jordani

Scientific name: Astyanax jordani

Common name: Blind cave tetra

Family: Characidae

Usual size in fish tanks: 7 - 8 cm (2.76 - 3.15 inch)

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Recommended pH range for the species: 6 - 7

Recommended water hardness (dGH): 18 - 30°N (321.43 - 535.71ppm)

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Recommended temperature: 20 - 25 °C (68 - 77°F)

The way how these fish reproduce: Spawning

Where the species comes from: North America

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Top levels

Origin

The Blind Cave Tetra (Astyanax jordani) is native to Mexico, where it inhabits the underground rivers and cave systems of the Sierra Madre Oriental. Over generations, these fish adapted to complete darkness, losing both pigmentation and eyesight. Instead, they developed heightened sensory abilities, relying on their lateral line system to navigate. Due to interbreeding with other tetra species, hybrids have been found further afield in Central America.

Short Description

The Blind Cave Tetra is a fascinating and resilient species, highly popular among aquarists due to its unique appearance and adaptability. Despite lacking eyesight, these fish are highly active and social, making them a great addition to community tanks. They reach an adult size of 7-8 cm (2.76 - 3.15 inches) and should be kept in groups of at least six to reduce stress and encourage natural behaviors.

Lifespan

With proper care, the Blind Cave Tetra can live between 3-5 years, though some specimens have been known to exceed this lifespan in optimal conditions.

General Care

Blind Cave Tetras are relatively undemanding when it comes to tank setup. A small group can be housed in a minimum tank size of 60 cm x 30 cm (2 feet x 1 foot), though larger groups will require an aquarium of at least 90 cm x 30 cm (3 feet x 1 foot) to provide adequate swimming space. These fish thrive in a variety of setups, whether in heavily planted tanks, rocky environments, or open aquascapes.

Recommended water parameters:

Temperature: 20 - 25°C (68 - 77°F)
pH: 6.0 - 7.0
Hardness: 18 - 30°N (321.43 - 535.71 ppm)

Like most tetras, they are generally peaceful but can occasionally nip at the fins of slow-moving or long-finned species, particularly during feeding.

Feeding

Blind Cave Tetras are not picky eaters and will readily accept a variety of foods. To maintain their health and coloration, provide a varied diet, including:

Staple diet: High-quality flake food or small sinking pellets.
Live or frozen treats: Brine shrimp, bloodworms, daphnia, and artemia.
Vegetable matter: Blanched spinach or spirulina-based flakes.

Feed small portions 2-3 times a day to prevent overeating and maintain water quality.

Sexing

Determining the sex of Blind Cave Tetras is relatively straightforward. Males tend to be slimmer and develop a curved anal fin, while females are slightly larger with a straighter anal fin and a rounder belly, especially when carrying eggs.

Breeding

Breeding Blind Cave Tetras is relatively simple, making them an excellent choice for aquarists looking to raise their own fish. To encourage spawning:

Set up a dedicated breeding tank with a sponge filter to prevent fry from being sucked in.
Use marbles or a fine mesh as a substrate to protect eggs from predation.
Introduce well-conditioned parent fish with a high-protein diet.

Spawning typically occurs in the early morning. The female scatters her eggs, and the male fertilizes them immediately. Since the parents exhibit no parental care and may eat the eggs, it is best to remove them after spawning.

The eggs hatch within 24 hours, but the fry will not require feeding until they become free-swimming. Once free-swimming, they should be fed:

Infusoria for the first few days.
Newly hatched brine shrimp once they grow slightly larger.
Crushed flake food after a few weeks.

Tank Mates

Blind Cave Tetras are social and do best in groups. They can be housed with other peaceful species, but avoid slow-moving or long-finned fish. Suitable tank mates include:

Neon Tetras – Small, peaceful companions.
Ember Tetras – Fast-moving and compatible.
Sterbai Corydoras – Gentle bottom dwellers.
Otocinclus Catfish – Peaceful algae grazers.

Tank mates to avoid:

Betta Fish – Their long fins may attract fin-nipping.
Angelfish – Potential for fin-nipping.
Oscars – Too large and aggressive.

Recommended Plants

While Blind Cave Tetras do not rely on plants for cover, adding vegetation enhances the aesthetic appeal and helps regulate water quality. Suitable plants include:

Java Fern – Low-maintenance and hardy.
Anubias – Great for low-light setups.
Cryptocoryne Wendtii – Ideal for soft water tanks.

Final Thoughts

The Blind Cave Tetra is a unique and hardy fish that brings intrigue to any aquarium. Despite its lack of eyesight, it navigates effortlessly using its lateral line system. By providing proper tank conditions, a well-balanced diet, and compatible tank mates, these fish will thrive and exhibit their fascinating behaviors.