Max Size: 12cm

Mexican Tetra (Astyanax mexicanus)

The Mexican Tetra is Hardy and peaceful and is an excellent choice for the beginner aquarist and suitable for most community aquariums, however slow of very timid tankmates are best-avoided. It occasionally nips at tankmates when feeding, but its searching technique causes this rather than aggression.

Although you cant describe this Tetra as sociable, it doesn't appear to fare any better when maintained in a group.

The Mexican Tetra has the usual characin shaped body and has undistinguished, drab colouration. It gets its name because it has no eyes or pigment. Its body is pinkish-white with silver linings on their body resembling that of an albino.

Even though these fish are blind, they can still, however, find their way around utilizing their lateral lines which are highly receptive to fluctuating water pressure.

Quick Facts
Scientific NameAstyanax mexicanus
Other NamesBlind Cave Fish, Blind Cave Characin, Blind Cave Tetra
OriginsMexico, USA
Aquarium LevelMiddle
DifficultyBeginner - Intermediate
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH6.5 - 8.0
GH5 - 30
TDS90 - 447
68 - 77℉
20 - 25℃

Photos of the Mexican Tetra

Mexican Tetra
Mexican Tetra
Mexican Tetra
Mexican Tetra
Mexican Tetra
Mexican Tetra
Mexican Tetras

Natural Habitat

The Mexican Tetra is native to the Nearctic realm, originating in the Nueces and Pecos Rivers, the Rio Grande in Texas as well as eastern and central parts of Mexico. They inhabit backwaters and pools of rivers and creeks with a rocky or sandy substrate and live in underground caves and caverns. In the winter season, some populations migrate to warmer waters.

What to feed the Mexican Tetra

It is not challenging to feed the Mexican Tetras, and their diet should comprise of high quality dried products such as flakes, granules and pellets alongside plenty of small live and frozen foods.

The fish relies on their sensing organ to find food so they may be a little bit slower in finding food in comparison to other fish species, so it is best to feed them often in a fixed period.

How to sex the Mexican Tetra

It is quite tricky to distinguish males from females; however, typically the anal fin of the male has a slightly curved edge, while the females tend to be straight and when in spawning the females are somewhat more extensive than the males.

How to breed the Mexican Tetra

It is relatively easy to breed the Mexican Tetra providing you meet a few requirements.

You will need a separate spawning tank with a suspended layer of mesh or similar on the bottom of the tank, and this will prevent the adults from consuming the eggs. The tank will need a simple air-powered sponge filter to help with water flow and oxygenation.

It would be best if you conditioned the sexes in separate tanks to avoid any undesired spawning events. The most well-conditioned male and female can then be removed and placed in the spawning tank in the evening.

The following morning you should notice eggs, remove the adults immediately. If you are still unable to see any eggs after about 24 hours, remove them and try a different pair.

This species of Tetra is a prolific breeder, and the females may lay up to 1000 eggs. These eggs are white and hatch within 24 hours, with the fry taking an additional 5-7 days to consume the yolk sac and become free-swimming.

Infusoria or other microscopic foods should then be offered for the first week or two, after which you can introduce nauplii, artemia or other suitably-sized dried products to the diet.

Some predation may occur within the brood, but with the amount of fry produced, this should not bestow a problem.

The fry appears to have normal eyes in the early stages of life, but these never develop fully and eventually sink completely, becoming covered with flesh.

Other Tetras of interest

African Moon Tetra(Bathyaethiops caudomaculatus)
African Red Eyed Tetra(Arnoldichthys spilopterus)
Black Darter Tetra(Poecilocharax weitzmani)
Black Line Tetra(Hyphessobrycon scholzei)
Black Neon Tetra(Hyphessobrycon herbertaxelrodi)
Black Phantom Tetra(Hyphessobrycon megalopterus)
View all Tetras
Date Added: 16/10/2020 - Updated: 02/12/2021 17:27:10