The Mexican tetra is a schooling fish (6), which can form schools of up to several hundred or even thousands of individuals (5). It is primarily a carnivorous fish, feeding on aquatic insects, crustaceans, worms, snails and smaller fish (2) (5), but it is also reported to feed on plant matter and algae (5).
In Texas, breeding activity has been observed in the surface-dwelling form from late April until September, although elsewhere, such as the lower reaches of the Rio Grande River, reproduction is said to occur year-round. Spawning taking place in late spring and early summer, when a mass of sticky eggs is released into the surrounding waters (5). Mexican tetras develop quickly, which relates to their short lifespan. Those that are born in the spring reproduce for the first time in autumn, and few live for longer than two years (5).