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Maximum size : 12 cm

Mexican Tetra - Astyanax mexicanus : Complete Fish Profile & Care Guide

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The Mexican Tetra (Astyanax mexicanus) is a hardy and peaceful fish, making it an excellent choice for beginner aquarists and a suitable addition to most community aquariums. However, it' s important to note that slow or very timid tankmates are best avoided, as these fish may occasionally nip at other fish while feeding. This behavior is typically caused by the Tetra' s searching technique rather than aggression, highlighting the importance of choosing compatible tankmates. While the Mexican Tetra is not known for being sociable, maintaining them in a group doesn' t appear to improve their behavior or overall wellbeing. Instead, these fascinating fish prefer to spend their time exploring their surroundings and engaging in natural behaviors. Despite their undistinguished, drab coloration, the Mexican Tetra is a unique and captivating species. In fact, they get their name from their lack of eyes and pigment, which gives their body a distinctive pinkish-white hue with silver linings resembling that of an albino. Interestingly, despite their lack of eyesight, these fish are still able to navigate their surroundings with ease. They do this by utilizing their highly receptive lateral lines, which detect even the slightest fluctuations in water pressure.

Mexican Tetra Photos

Sexual Dimorphism

Distinguishing between male and female Mexican Tetras can be a challenging task for aquarium enthusiasts. However, one method of differentiation involves examining the anal fin. Typically, the male Mexican Tetra will have an anal fin with a slightly curved edge, while the female' s anal fin tends to be straight. Additionally, during spawning, females may appear more extensive than males, providing another potential means of identification.

Quick Facts

Scientific NameAstyanax mexicanus
Year Described1853
Other NamesBlind Cave Fish, Blind Cave Characin, Blind Cave Tetra
OriginsMexico USA
Max Size12 cm
Aquarium LevelMiddle
DifficultyBeginner - Intermediate
Best kept asN/A
Lifespan3 - 5 years

Water Parameters

Water TypeFreshwater
PH6.5 - 8.0
GH5 - 30
TDS90 - 447
68 - 77
20 - 25

Natural habitat

The Mexican Tetra, a captivating freshwater fish, is native to the Nearctic realm and can be found in a range of waterways throughout Texas and Mexico. These fish are particularly prevalent in the Nueces and Pecos Rivers, as well as the Rio Grande. In their natural habitat, Mexican Tetras inhabit backwaters and pools of rivers and creeks, preferring areas with a rocky or sandy substrate. Interestingly, these fish have also been known to seek shelter in underground caves and caverns, adding to their allure and mystique. During the winter season, some populations of Mexican Tetras are known to migrate to warmer waters in search of more hospitable conditions. This behavior highlights the remarkable adaptability and resourcefulness of these fascinating fish, further underscoring their importance and value within their natural ecosystem. Overall, the Mexican Tetra is a remarkable species that showcases the diversity and wonder of the Nearctic realm.

How to breed the Mexican Tetra

Breeding the Mexican Tetra can be a relatively straightforward process, provided that certain requirements are met. First and foremost, a separate spawning tank equipped with a suspended layer of mesh or a similar material on the bottom should be utilized to prevent the adults from consuming the eggs. Additionally, a simple air-powered sponge filter should be employed to help maintain proper water flow and oxygenation. To avoid any unwanted spawning events, it' s recommended to condition the sexes in separate tanks. Once the most well-conditioned male and female have been identified, they can be placed in the spawning tank in the evening. By the following morning, eggs should be visible, at which point the adults should be promptly removed. If no eggs are visible after about 24 hours, it may be necessary to try a different pair. Mexican Tetras are prolific breeders, and females may lay up to 1000 eggs. These eggs are white and hatch within 24 hours, with the fry becoming free-swimming after an additional 5-7 days, having consumed the yolk sac. For the first week or two, infusoria or other microscopic foods should be offered to the fry, followed by nauplii, artemia, or other suitably-sized dried products. Some predation may occur within the brood, but with the high number of fry produced, it should not present a significant problem. Interestingly, the fry of Mexican Tetras appear to have normal eyes in the early stages of life, but these never develop fully and eventually sink completely, becoming covered with flesh. This unique trait adds to the allure of these fascinating fish and provides further insight into their behavior and natural habitat.

Diet & feeding

Maintaining a well-balanced and nutritious diet for the Mexican Tetra is essential for their overall health and vitality. Fortunately, feeding these fish is a relatively straightforward process that involves a combination of high-quality dried products, such as flakes, granules, and pellets, alongside plenty of small live and frozen foods. It' s important to note that Mexican Tetras rely on their highly developed sensing organs to locate food, which may cause them to take longer to find and consume food compared to other fish species. To accommodate this, it' s recommended to feed them often during a fixed period, ensuring that they receive adequate nutrition and maintaining their overall health and wellbeing. Providing a diverse and nutritious diet is a critical aspect of responsible aquarium ownership, and it' s essential to consider the unique dietary needs of each species in your care.

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