West Texas Shiner, Notropis megalops

West Texas Shiner, Notropis megalops. Fish caught from Río Ramos, Nuevo León, August 2014. Length: 6.0 cm (2.4 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

The West Texas Shiner, Notropis megalops, is a member of the Carp and Minnow or Cyprinidae Family, and is known in Mexico as carpa oeste texana. Globally, there are eighty-eight species in the genus Notropis, of which fifteen are widespread throughout Mexico’s freshwater systems.

The West Texas Shiner has a deep laterally compressed fusiform body that is deepest just behind the pectoral fins. They are dark brown to black dorsally with prominent darkly outlined scales transitioning to silvery-white ventrally. They have a dark horizontal line that extends from the head to the caudal base. Their fins are transparent. Their head is large and elongated with a pointed snout with large eyes that are wider than the snout and a large terminal oblique mouth that has thin lower lips without fleshy lobes and a protractile mouth. Their anal fin has 3 spines and 10 or 11 rays; their caudal peduncle is wide; their caudal fin is concave with wide rounded equal sized lobes; their dorsal fin has 3 spines and 8 rays and is pointed with a narrow base, their pectoral fins have 1 spine and 13 or 14 rays and are large; and, their pelvic fins have 1 spine and 7 rays and are small. They have 8 or 9 gill rakers on the first arch. They are covered with large scales. Their lateral line is straight and complete.

The West Texas Shiner is a freshwater benthopelagic schooling species that is found in streams with moderately fast currents with clear waters over gravel, rubble and sand substrate and in pools. They are intolerant of high salinity. They reach a maximum of 6.6 cm (2.6 inches) in length. They consume aquatic insects, algae, terrestrial insects and detritus. Reproduction occurs in small groups with broadcast spawning with early maturation, long spawning seasons and multiple batches. They have life spans of two years.

The West Texas Shiner is native to the freshwater systems of northeastern mainland Mexico being limited to the Atlantic slope of the Río San Diego and Río Ramos of the Río Grande drainage in the States of Coahuila and Nuevo León.

The West Texas Shiner is a straight forward identification that might be confused with the Rio Grande Shiner, Notropis jemezanus (eyes wider than the snout; lack the black mid-lateral stripe boarded with a white stripe) and the Texas Shiner, Notropis amabilis (body deepest midway between pectoral and pelvic fins; triangular dorsal fin with a wide base; lighter dorsally; darker mid-lateral stripe). The West Texas Shiner 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.

From a conservation perspective the West Texas Shiner has not been formally evaluated. Their long-term survival is threatened by changes in water quantity and quality with pollution caused by human development including dam construction and the introduction of foreign taxa. They are small in stature, rare, and of limited interest to most.