Banded Tetra, Astyanax aeneus

Banded Tetra, Astyanax aeneus, Female. Fish caught from Barton Creek, Belize, October 2012. Length: 12 cm (4.7 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.

Banded Tetra, Astyanax aeneus. Underwater photograph taken within the within the Sian Ka’an Biosphere Reserve, Quintana Roo, March 2021. Photograph and identification courtesy of Marina Sutormina, Stockholm, Sweden.

Banded Tetra, Astyanax aeneus. Underwater photograph taken in Cenote Azul, Quintana Roo, December 2020. Photograph courtesy of Bob Hillis, Ivins, Utah. Identification courtesy of Dr. John Lyons, Madison, Wisconsin.

The Banded Tetra, Astyanax aeneus, is a member of the Tetra or Characidae Family, and is known in Mexico as pepesca. Globally, there are one hundred forty-seven species in the genus Astyanax, of which three are found in the freshwater systems of mainland Mexico. The Astyanax Genus was named after Astyanax, the son of Hector of Troy in Greek mythology (not easily confused with Helen).

The Banded Tetras have fusiform bodies with a depth that is 30% to 34% of standard length. They are very colorful being greenish-brown dorsally and transitioning to silver then to white ventrally. Their colors vary from location to location with more brightly colored fish being found in murky environments. Their caudal fin is red or yellow. The key to identification is the presence of a black rhomboidal blotch on their caudal peduncle that extends to the center of their caudal fin. They have transparent fins with minimal dark red pigments on the first rays of their anal and dorsal fins. Their head has a small slightly upturned terminal mouth and large eyes placed directly behind the mouth. Their anal fin has 3 or 4 spines and 22 to 30 rays; their caudal fin is deeply forked; their dorsal fin has 2 spines and 8 or 9 rays and is followed by a small adipose fin on the caudal base above the anal fin; and, their pectoral fins have 1 or 2 spines and 10 to 14 rays. They have 19 to 26 gill rakers. They are covered with large scales.

The Banded Tetra is a benthopelagic schooling species found in all types of freshwater environments from fast flowing rivers and streams to marshes and stagnant pools. They reach a maximum of 14 cm (5.5 inches) in length with females being larger than males. They are found from sea level to elevations of 1,000 m (3,300 feet). They feed on algae, seeds, leaves, aquatic and terrestrial insects, and fish fry. The Banded Tetra is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Banded Tetras are native to the freshwater systems of southeast and southwest mainland Mexico including the Champotón, Campeche, the Colima, Colima and the Papaloapan Rivers, Veracruz.

The Banded Tetra is straightforward to identify and cannot be confused with any other species due to the prominent black tail blotch.

The Banded Tetras are very abundant in many locations. They have not been evaluated from a conservation perspective but should be considered of Least Concern. They are caught in abundance via nets in lake shallows and used as bait fish, for food, by the aquarium trade, and for monitoring aquatic environmental quality in areas that have significant pollution from agrochemical residues. They are also an important contributor to their aquatic ecosystems as they excrete disproportionately large amounts of phosphorous, with levels ten-fold higher than other species in the same environment.