The Gila chub (''Gila intermedia'') is a species of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

in the family

Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest verte ...

. It is found in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. The Gila chub is closely related to the roundtail chub.Rinne, J.N. 1969. ''Cyprinid fishes of the genus Gila from the lower Colorado River basin''. Masters thesis, Arizona State University, Tempe. This species is commonly found in association with the

Gila topminnow The Gila topminnow or charalito (''Poeciliopsis occidentalis'') is a species of fish in the family Poeciliidae. It is found in Mexico and the United States. Description The Gila topminnow has an elongated curved body. Males are rarely over and ...

, the

desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...

and

Sonora sucker The Sonora Sucker (Gila Sucker), ''Catostomus insignis'', is a medium-sized catostomid The Catostomidae are the suckers of the order Cypriniformes, with about 78 species in this family of freshwater fishes. The Catostomidae are almost exclu ...

, and the

longfin The longfins, also known as roundheads or spiny basslets, are a family, Plesiopidae, which were formerly placed in the order Perciformes but are now regarded as being ''incertae sedis'' in the subseries Ovalentaria in the clade Percomorpha. They ...

and

speckled dace The speckled dace (''Rhinichthys osculus''), also known as the spotted dace and the carpita pinta, is a member of the minnow family. It is found in temperate freshwater in North America, from Sonora, Mexico to British Columbia, Canada. Canada is ...

Description

The Gila chub has a large, chubby body, with large, thick scales. The body is dark overall, and sometimes is lighter on the belly. In larger females, a soft, fat, and broad hump sometimes develops on the nape of the neck. Mature, breeding males have a red or orange color on the lower cheek, back parts of the lips, and on parts of the fin. This coloration can also be found on the male's caudal peduncle (tail side).Minckley, W.L. 1973. ''Fishes of Arizona.'' Arizona Game and Fish Department, Phoenix. pp. 104-106. Males usually grow to be only about 15 cm (5.9 in), while females can reach to 25 cm (9.8 in)—a significant difference.Rinne, J.N. and W.L. Minckley. 1991. Native fishes of arid lands: a dwindling resource of the desert southwest. U.S. Department of Agriculture, Forest Service, General Technical Report RM-206. Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado. pp. 24-25.

Range

The Gila chub has been found in streams of the

Gila River The Gila River (; O'odham ima Keli Akimel or simply Akimel, Quechan: Haa Siʼil, Maricopa language: Xiil) is a tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of n ...

drainage in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, and in the Santa Cruz River system in

Sonora, Mexico Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. The state is divided into 72 municipalities; the ...

; however, recently, the Gila chub species has not been documented in the San Pedro drainage in Sonora, Mexico. The Gila chub has also been recently discovered in these specific drainages in Arizona: Santa Cruz River, Middle Gila River, San Pedro River,

Agua Fria River The Agua Fria River (Spanish for "cold water") is a long intermittent stream which flows generally south from east-northeast of Prescott in the U.S. state of Arizona. Prescott draws much of its municipal water supply from the upper Agua Fria w ...

, and the

Verde River The Verde River (Yavapai: Haka'he:la) is a major tributary of the Salt River in the U.S. state of Arizona. It is about long and carries a mean flow of at its mouth. It is one of the largest perennial streams in Arizona. Description The ri ...

. These fish have also been extirpated from the Monkey Spring of the Santa Cruz River, and Fish and Cave Creeks of the Salt River.

Habitat

Gila chub of the Gila River basin usually occupies the smaller headwater streams, springs or marshes. Their choice of diverse habitats varies, depending on the season or age of the fish. Juveniles are found in riffles (a patch of waves), pools, and banks. However, in larger streams, these fish are found in parts of heavy vegetation, for cover and foraging. Gila chubs are also considered to be highly “secretive” when it comes to habitats; since fish of this species are constantly looking for deeper waters near cover and shade.

Diet

Gila chubs are

omnivores An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutri ...

, and their diet mainly includes aquatic (and terrestrial) insects. These fish are also known to consume other fish at large sizes, which include eating

(''Rhinichthys osculus'') and other small cyprinid fish. Juveniles feed throughout the day while the adults are out during the early morning and late night; juveniles usually consume insects and algae.

Reproduction

Gila chub have a unique breeding season, which occurs from late spring to summer (some populations can go as far as late winter if the water temperature stays constant). The breeding period is long because Gila chub mature in their second or third year, and are more active at this age. Reproduction occurs in heavily vegetated areas. Actively breeding fish have distinct intense coloration—parts of the body become fire-red (ventro-lateral surfaces) and the eyes transform to a yellow-orange.

Conservation

Little is known about the population of Gila chub in Mexico, but the populations that reside in Arizona are expected to decrease because of these ongoing threats: aquifer pumping, stream diversion, habitat alterations by non-native crayfishes, and mainly, predation/competition with nonnative fishes. Currently, the Gila chub are sharing the waters with

green sunfish The green sunfish (''Lepomis cyanellus'') is a species of freshwater fish in the sunfish family (Centrarchidae) of order Perciformes. A panfish popular with anglers, the green sunfish is also kept as an aquarium fish by hobbyists. They are us ...

(''Lepomis cyanellus'') in many areas; however, introducing any other kind of exotic fish to the Gila chub must be managed and observed (it is crucial to their survival). In fact, the Gila chub has been extirpated on many occasions because of exotic fish such as the

largemouth bass The largemouth bass (''Micropterus salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, but ...

(''Micropterus salmoides''). According to the Arizona Fish and Game Department, the Bureau of Land Management Phoenix District is proposing translocations of the Gila chub from Silver Creek to an adjacent stream in the Agua Fria headwaters. Here, the Arizona Game and Fish Department can complete their status review of warranting the Gila chub under the Endangered Species Act.

References

Sources

{{Taxonbar, from=Q308094 Chubs (fish) Gila (fish) Taxa named by Charles Frédéric Girard Fish described in 1856 Freshwater fish of Mexico Freshwater fish of the United States Taxonomy articles created by Polbot ESA endangered species