X-ray tetra
Pristella maxillaris
Texan Tetra
Astyanax argentatus
About
A small, silvery tetra that lives further north than any of its relatives, thriving in the clear spring-fed waters of a single Texas river system.
Appearance
A slender, silvery fish with a darker back and a belly tinted faintly red. Most fins show a faint orange or red-yellow color, and a black spot sits on the base of the tail, spreading onto the central tail rays. A second, variable dark mark sits just behind the gill cover, which can look rectangular, triangular, or barely visible.
Habitat
Lives in the clear, cool, spring-fed waters of the upper Nueces River in Texas, with a healthy strip of streamside plants along its banks. It has also been found in the Mexican state of Nuevo León.
Conservation
Listed as least concern by the IUCN. Although its population is fragmented, it is often one of the most common fish found at sites where it occurs. Small-scale pollution from nearby hiking trails and campgrounds puts minor pressure on its habitat, but rules limiting vehicle use in the watershed now help protect the riverside zone.
Did you know?
This is the northernmost species in its entire genus, found further from the tropics than any other tetra in the Astyanax group.
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