Red Grayhorse, Moxostoma congestum
Red Grayhorse, Moxostoma congestum. Fish caught from the Independence Creek, Sheffield, Texas. June 2021. Length: 41 cm (16 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Red Grayhorse, Moxostoma congestum. Fish caught from a freshwater stream in Puerto Chomes, Costa Rica, March 2021. Length: 46 cm (18 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
Red Grayhorse, Moxostoma congestum. Fish caught from the Llano River, Southwest Texas, February 2022. Length: 39 cm (15 inches). Catch, photograph, and identification courtesy of Chris Moore, Peoria, Arizona.
Red Grayhorse, Moxostoma congestum. Fish caught from the Llano River, Southwest Texas, February 2022. Length: Weight: 56 cm (22 inches). Weight: 2.3 lb (5 lbs 0 oz). Catch courtesy of Brayden Moore, Peoria Arizona. Photograph, and identification courtesy of Chris Moore, Peoria, Arizona.
The Gray Redhorse, Moxostoma congestum, is a member of the Sucker or Catostomidae Family, and is known in Mexico as matalote gris rank. Globally, there are twenty-two species in the genus Moxostoma, of which three are found in all freshwater systems of Mexico.
The Gray Redhorse has a cylindrical fusiform body. Dorsally they are an overall grayish black or a yellowish brown to greenish transitioning to silvery sides and white ventrally Their caudal fin is dusky, the dorsal fin is partly dusky and streaked with black. Their head is large, has a broad snout, a prominent ventral subterminal small mouth. Their anal fins have 6 or 7 rays; the caudal fin has 18 rays; their dorsal fin has 11 or 12 rays, their pectoral fins have 15 or 16 rays; and their pelvic fins have 9 rays. They have a complete and well-developed lateral line. They are covered with large scales. The males and females have similar colorations but the males have nuptial tubercles on the anal fin and the ventral lobe of the caudal fin and a few on the pectoral fins. They are normally present in 1:1 sex ratios.
The Gray Redhorse are found in upland and lowland rivers and streams in rock, sand, or gravel bottomed pools and deep runs of creeks and rivers; they also occur in some reservoirs. Young and subadults form loose schools in riffles and gravelly runs. Adults usually found in stream pools with firm substrate of sand or silt and are able to tolerate moderate turbidity. They reach a maximum of 65 cm (2 feet 2 inches) in length. As of January 1, 2023, the International Game Fish Association world record stood at 1.59 kg (3 lbs 8 oz) caught in Fort Stockton, Texas in February 2022. They are an opportunistic benthic invertivore that consume aquatic insects, larvae, mollusks, amphipods, ostracods and small amounts of fish. In turn they are preyed upon by Smallmouth Bass, Micropterus dolomieu. Reproduction is oviparous and polygynandrous (promiscuous). Spawning occurs in the spring when water temperatures reach 16.5oC (62oF) with the adults migrating upstream to clear creeks with depths between 3 m (10 feet) and 6 m (20 feet). The adhesive eggs are buried in loose gravels where they hatch in a few days. They are subject to massive die offs during toxic algal blooms. They have life spans of at least five years. The Gray Redhorse 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 Gray Redhorse is very similar to and easily confused with the West Mexican Redhorse, Moxostoma austrinum (dark crescents on upper body scales). The black-banded membranes in the dorsal and caudal fins of the Gray Redhorse distinguish it from all other species of redhorses found in the United States. The Grey Redhorse can be separated from other terete suckers by the plicate folds on the lips and membranes of the dorsal fins streaked with black.
The Gray Redhorse is native to the Southwest United States and Northern Mexico. In Mexico they are found in the Atlantic drainage of the Nazas, Mezquital, Rio Grande and the Rio Soto la Marina Rivers in the states of Chihuahua, Coahuila, Nuevo León and Tamaulipas.
From a conservation perspective the Gray Redhorse is currently considered to be of Least Concern with stable, widely distributed populations, however their populations in Mexico have declined significantly recently. Their populations and long-term viability are currently threatened by dam construction and related habitat destruction by human development causing the decline in water quality and by overfishing. They have also been eliminated from some areas by human trash fish eradication programs. They have limited populations and are prone to overfishing.