Longnose Dace, Rhinichthys cataractae

Longnose Dace, Rhinichthys cataractae. Fish caught from Duffins Creek, Pickering, Ontario, Canada, June 2014. Length: 7.6 cm (3.0 inches). Catch, photograph, and identification courtesy of Kenneth Tse, Toronto, Ontario, Canada.

Longnose Dace, Rhinichthys cataractae. Fish caught from a small creek in the Jemez Mountains, New Mexico, July 2017. Length: 9.5 cm (3.7 inches). Catch, photograph, and identification courtesy of Ben Cantrell, San Diego, California.

Longnose Dace, Rhinichthys cataractae. Fish caught from the Colorado River in Moab, Utah, June 2018. Length: 11 cm (4.3 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.

Longnose Dace, Rhinichthys cataractae. Fish caught from a small creek in Ruidoso Downs, New Mexico, July 2019. Length: 9.5 cm (3.7 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

The Longnose Dace, Rhinichthys cataractae, is a member of the Carp and Minnow or Cyprinidae Family, that is also known as the Great Lakes Longnose Dace and in Mexico as carpita rinconera. Globally, there are nine species in the genus Rhinichthys of which three are found in the freshwater systems of Mexico.

The Longnose Dace has an olive brown to dark red-purple color dorsally that transitions to a lighter yellow ventrally. Some individuals have small dark brown spotting and mottling on their sides. The juveniles have a dark lateral stripe that extends from the tip of the snout to the caudal base that fades with maturity. They have a dusky caudal spot. The corners of the mouth, cheeks and the bases of the anal, pectoral and pelvic fins are bright red in breeding males. Their head has a rounded fleshy projecting snout that extends past the subterminal sucker-like mouth, with a very small barbel at the corner. Their anal fin has 7 to 9 rays with the lower lobe elongated in females; their dorsal fin has 7 to 9 rays and originates slightly before the pelvic fins.

The Longnose Dace is a demersal, schooling species found in freshwater systems that have temperatures between 4°C (39°F) and 16°C (61°F). They are highly adaptable and can be found in both clear and cold streams and lakes, as well as in muddy and warm waters. They have a small home range and  high site fidelity. They are found in gravel and rubble riffles or fast creeks and in small to mid-sized rivers and along the rocky shorelines of lakes at depths up to 10 m (33 feet). They are known to migrate to deeper waters in summer during periods of elevated water temperatures. They reach a maximum of 22.5 cm (8.9 inches) in length, with females being larger than males. They are nocturnal feeders that consume aquatic insects, including blackflies, mayflies and midges, terrestrial insects, invertebrates and fish eggs. The juveniles consume algae and diatoms. In turn they are an important forage fish for larger predatory fish and are also consumed by birds, specifically herons. They utilize their cryptic colorations to avoid predation. Reproduction occurs in loose gravel substrate and is oviparous and polyandrous (promiscuous) with each sex having multiple spawning partners. Each female will produce between 1,000 and 10,000 eggs and can spawn up to six times per year. Fertilization occurs externally and the benthic eggs hatch in 3 to 10 days. The juveniles are pelagic and remain inshore for four months before transitioning to bottom dwelling. They are known to hybridize with the Central Stoneroller, Campostoma anomalum and the Rio Grande Chub, Gila pandora. They have life spans of five years.

The Longnose Dace is a straightforward identification that is most likely confused with the Blacknose Dace, Rhinichthys atratulus (dark lateral stripe in juveniles and adults; not found in Mexico).

The Longnose Dace has the widest range of any North American minnow, being found from the Arctic Circle to Mexico and from the east coast to the west coast of the United States. In Mexico they are found in the Rio Grande drainage in the northern portions of the country.

From a conservation perspective the Longnose Dace is currently considered to be of Least Concern with stable, widely distributed populations. They are prone to habitat destruction and the disappearance of natural water supplies and interactions with newly introduced non-native fishes. They are utilized primarily as a baitfish and on a limited basis by the aquarium trade. They are also raised via aquaculture.