The Mexican Tetra (Astyanax mexicanus) is a small freshwater fish native to the rivers and caves of Mexico and parts of the United States. It typically measures about 2 to 3 inches in length and is known for its transparent body and distinctive silver coloration. This species is often studied for its unique adaptations, particularly the cave-dwelling variety, which has lost its eyesight over generations. Mexican Tetras are popular in the aquarium trade due to their hardiness and ease of care. They thrive in schools and prefer well-planted tanks with plenty of swimming space. Their diet consists of small insects, crustaceans, and plant matter, making them omnivorous.