Fish Tanks and Ponds

A comprehensive guide to fish

Astyanax jordani

Blind cave fish

Blind cave fish, Astyanax jordaniBlind cave fish, Astyanax jordani
Photos by Andy Rapson

Etymology:

Astyanax: The name of Astyanax, Hector´s son in the Greek mithology.

General Notes:

Blind cave fish are well able to compete for food and look after themselves in a community aquarium with sighted fish. Although they would probably look far more stunning in a biotope aquarium which replicated the natural habitat as far as is possible. Blind cave fish have eyes when they hatch from their egg and although their eyes are still present they are covered with skin long before the fish reach adulthood. There are many theories about this but the most popular theory is that having eyes in total darkness is a liability rather than advantageous, eyes are delicate and in darkness in a rocky habitat they may be prone to injury and so through natural selection the eyes have been lost.
To compensate for being blind Astyanax jordani have an improved senses of taste and is able to store fat more efficiently than other species of fish which means the fish is better able to find food in darkness and use it more efficiently.
Blind cave fish do live in groups but it isn't essential to keep them in a group in captivity, they seem just as comfortable living in pairs or even singly with other species. There is a lot of confusion about the taxonomy of this species. As we understand it the Mexican blind cave fish Astyanax mexicanus has a blind form which is still classed as A. mexicanus. Astyanax jordani evolved separately and is a distinct but very similar species.

Feeding

Wild Astyanax jordani have to rely on food items which drift in to the cave systems where they live which for the most part is various insects and their larva. In captivity they are completely unfussy and will accept flake food, pelleted food, freeze dried food, Along with live or frozen food. In a community aquarium they behave as though they have eyes and seem to be at no disadvantage at feeding time.

Sexing

Females tend to be larger and more plump when adult than the males.

Breeding

Blind cave fish are one of the easier Characins to breed. A well cared for pair will spawn regularly without any special care although if you want to raise some fry a separate breeding tank will be needed. Their eggs are white and look like they are infertile but most will hatch. The parent fish have to be removed from the breeding tank immediately after spawning or they will eat their own eggs. The fry once free swimming can be fed using a commercial liquid fry food for the first few days before moving on to newly hatched baby brine shrimps and then finely powdered flake food.

Wild status

Wild populations of Astyanax jordani are vulnerable which means they are facing a high risk of extinction in the wild in the medium-term future.

Information at a glance

pH: 6 - 7.8
dGH: 4 - 30
Temperature: 20 - 25°C (68 - 77°F)
Lighting:
Diet: Omnivore
Size: 10cm (4in)
Min tank size: 60 litres
Difficulty level: Easy
Aquarium type: Community
Swimming level: All levels

Distribution and habitat

distribution map for Astyanax jordani

Origin: North America and Mexico.

Habitat: Subterranean water ways

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Astyanax
Species: A. jordani (Hubbs & Innes, 1936)

Common name: Blind cave fish

Synonyms: Anoptichthys antrobius, Anoptichthys hubbsi, Anoptichthys jordani, Astyanax mexicanus jordani