blind cave fish

Astyanax jordani
Family Characidae
Genus Astyanax
IUCN category (World) EN
Astyanax jordani Astyanax jordani

Introduction

Descriptor : Hubbs & Innes, 1936

Astyanax jordani, also known as blind cave fish, is a species of fish endemic to Mexico that inhabits underground rivers and caves. Descended from Astyanax mexicanus, these fish have developed a troglodytic lifestyle over time. The taxonomy of this species is still subject to change.

Over time, they have lost their pigmentation and the use of their eyes, although juveniles still hunt various invertebrates. Adults are primarily detritivores.

Who is it?

Morphology

  • Average size
    8 cm
  • Maximum size
    10 cm
  • Longevity
    8 year
  • Shape
    Oval
  • Average size
    8 cm
  • Maximum size
    10 cm
  • Longevity
    8 year
  • Shape
    Oval

How to recognize This fish ?

The blind cave fish measures between 8 and 10 cm. This troglodytic species is distinguished from its surface form by the absence of functional eyes and pigmentation. The skin is pale and translucent, while the head often presents a bulge where the eyes used to be.

Sexual dimorphism

There is no marked sexual dimorphism, with differences mainly occurring during reproduction.

Behaviour & Life cycle

  • diet
    carnivorous
  • Sociability
    living in shoals
  • territorial
    No
  • Way of living
    diurnal

This species lives in schools or small groups in the total darkness of the limestone caves of Mexico. Devoid of vision, it navigates using developed sensory organs that detect water vibrations and pressure variations. Its digestive microbiome allows it to exploit poor and variable resources. Young stages feed on small aquatic invertebrates (cladocerans, copepods, insects), while adults mainly consume detritus, including bat guano, as well as whole insects that have fallen into the caves.

Reproduction

  • Reproduction
    ovipare qui pond en eau libre

The blind cave fish is an oviparous fish that spawns freely in water. The female releases her eggs dispersedly, often above substrates with crevices and pores. The adhesive eggs lodge in these crevices, reducing the risk of predation by adults or other cave inhabitants. Reproduction is not strictly seasonal, but depends on local conditions, including nutrient inputs from floods or bat activity.

Harmless species

This species does not pose a particular danger to humans when encountered in its natural environment.

Origin and distribution

Natural range
Invasive range
Mixed / unknown area

Geographic distribution & Conservation

Astyanax jordani is endemic to Mexico. It lives in underground rivers and caves in the Sierra Madre Oriental in the northeast of the country. More than 200 caves have been identified in the Sierra de El Abra, where this species lives. Astyanax jordani has been observed in 31 different caves, with Cueva Chica as the type locality, as well as in around thirty other caves scattered across three different mountainous regions. These caves include Cueva de Los Sabinos, Sótano del Soyate, and Cueva del Fraile.

Conservation status of populations (IUCN)

World : EN

Where to see this species?

What is its habitat?

Natural environment characteristics

  • Temperature
    23 - 26 °C
  • pH (acidity)
    6.8 - 7.3
  • gh (hardness)
    6 - 10
  • Flow
    Medium and Slow

Biotope presentation

This species is confined to aquatic underground environments, living in lakes, ponds, and underground rivers of the Mexican karst. Most populations are found in the vadose zone, but some occupy the deep phreatic zone. Habitats are characterized by the absence of light, large water level fluctuations, and very limited food availability. Juveniles are sometimes carried into temporary areas during floods.

Main recommendations for fishkeeping

Deontology

In order to preserve wildlife, if you acquire this animal, it must not be released into the wild. See also, the Fishipedia charter.

Fishipedia supports the practice of responsible and environmentally friendly aquarium keeping. We encourage maintenance if it is motivated by a desire to understand the biological functioning of living things and if it is done with respect for animal life.

We believe that aquaristics is an opening to the discovery of aquatic environments, especially freshwater, and that this knowledge is necessary to better protect and respect these environments. Logically, we refute the compulsive purchase of animals that would not find a sufficient and / or adapted place in the host aquarium.

Our recommendations

  • Min volume
    120 liters
  • Population min
    10
  • Temperature
    23 - 26 °C
  • pH (acidity)
    6.8 - 7.3

Characteristics

  • Difficulty breeding
    moderate
  • Robustness
    tolerant
  • Behaviour
    peaceful
  • Availability
    rare

Recommended equipment from our partners

General reminders

It is strongly advised to read the complete dedicated file and to get information on the feedbacks of maintenance of the envisaged animal, this to avoid any potential conflict whose end result is generally the death of the individual (or the other inhabitants). It is important not to overload your aquarium to limit pollution. This will make maintenance easier.

In nature, animals are subject to weather conditions and live in waters with variable characteristics. The recommendations offered by our team for aquarium maintenance are a guidance and cannot be assimilated to scientific datas.

General reminder on maintenance datas

Le démarrage d'un aquarium est une partie primordiale pour l'équilibre et le bien-être des poissons. Lorsque l'on met en eau un aquarium, l'eau passe naturellement par un cycle biologique : le cycle de l'azote. Celui-ci dure environ trois semaines. Tous les 2 jours, nous vous conseillons de tester votre eau jusqu'à ce que le taux de nitrite soit à zéro pendant plusieurs jours d'affilée.

Pour accélérer ce cycle, vous pouvez utiliser un activateur de bactéries comme JBL Denitrol. Cette solution riche en bactéries vivantes et enzymes permet une mise en place rapide du cycle de l'azote. Les poissons peuvent alors être introduits plus rapidement.

Il est important de tester l'eau de son aquarium régulièrement pour maintenir un environnement sain pour les poissons et les autres habitants. Les tests d'eau permettent de mesurer les niveaux de différents paramètres tels que le pH, la dureté totale, ainsi que les taux de nitrates, de nitrites et d'ammoniaque.

Pour réaliser ces tests, vous pouvez utiliser des produits d'analyse spécialisés tels que JBL ProScan qui permet de réaliser un diagnostic de l'eau directement via un smartphone. Il existe également des coffrets de tests plus classiques de bandelettes, comme JBL PROAQUATEST.

En cas d’usage de l’eau du robinet, vous pouvez utiliser un conditionneur d’eau de type Biotopol de JBL pour éliminer les substances nocives comme le chlore, le cuivre, le plomb et le zinc. Une eau trop dure ou trop calcaire peut être inadaptée à de nombreuses espèces tropicales d’eau douce. Si nécessaire, vous pouvez la couper avec de l’eau osmosée ou de pluie filtrée afin d’obtenir une dureté plus adaptée aux besoins de vos poissons et de vos plantes. Les conditionneurs d'eau garantissent une meilleure santé aux poissons et une meilleure croissance des plantes.

Chlorine and chloramine are dangerous for the health of animals. Used to disinfect water, these agents are present in significant quantities in tap water. We recommend using an anti-chlorine agent every time you change the water. In addition to chlorine, treatments and medicines sold for aquarium use sometimes contain dangerous heavy metals in high doses.

Specific needs for the blind cave fish

The blind cave fish is a species which lives naturally at a temperature between 23 °C and 26 °C. Nitrate levels should remain below 50mg/L. To keep the water clean and unpolluted, plan on changing 20% to 30% of the water volume each month.

The breeding of this species is accessible on condition of being well informed about its needs in aquarium . Any cohabitants must be chosen with care to avoid the loss of animals.

This species is very rare in the aquarium trade. Instead, it is maintained by knowledgeable aquarists who own and breed individuals from wild origin strains. If you want to get this species, we advise you to contact specialized clubs. }Specimens from long time breeding are a bit easier to breed but you have to respect the particular water parameters.

Cohabitation & Environment

Being a living in shoals fish, it is advisable to install at least 10 individuals in an aquarium of 120 liters minimum. Group maintenance is a prerequisite to ensure their well-being. Lonely individuals tend to quickly become stressed and become especially susceptible to disease. Although sometimes certain groups can "merge", mixing several gregarious species living in the same zone of life is not recommended if the volume is not consequent.

The blind cave fish is a peaceful species that generally does not exhibit behavioral problems in a community aquarium.

To best reproduce the biotope of this species, you can cover the bottom of the tank with sand and put a pile of stones to form caves.

Tips for feeding

The blind cave fish is carnivorous.

This species can eat dry food (flakes, pellets), fresh food and frozen food. To avoid deficiencies, it is recommended to vary the types of food.

Feed animals in moderation to maintain good water quality. Meals should be eaten within 2–3 minutes, served in several small portions rather than a single large ration.

Uneaten food quickly decomposes, releasing ammonia, nitrites, and nitrates, which disturb the aquarium’s biological balance.

Make sure each species can access food properly, slower or bottom-dwelling individuals may require targeted feeding.

Food recommendations from our partner JBL - Products PRONOVO

Reproduction protocol

  • Maintenance difficulty
    very hard
  • egg-laying protection
    No

Hybridization risks

In general, it is advised not to mix several species of the same genus or different varieties of the same species, to avoid the risks of hybridization.

These plants might interest you

Plants play a crucial role in aquariums, both for their ability to filter water by absorbing excess nutrients and for their aesthetic contribution. They provide fish with natural hiding places, can serve as breeding sites, and generally help maintain the overall balance and optimal conditions of the aquarium. The selection presented here includes species from the same regions as the species described on this page, although they do not necessarily come from its exact natural biotope.

To go further

Species of the same family

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To read on the web

Sources & Contributions

Participation & Validation

The Fishipedia team and specialist contributors are committed to providing high-quality content. However, although the information comes from scientific sources or testimonials from specialists, the cards may contain inaccuracies.

Benoit Chartrer

Benoit Chartrer

Translation

Translation done with the valuable contribution of our translators, who make this information available to a wider audience. We sincerely thank them for their commitment.

Marine Kassel

Marine Kassel

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Template and content © Fishipedia - Unauthorized reproduction without prior request - ISSN 2270-7247 - Last modification 10/11/2023

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