The arroyo chub (''Gila orcuttii'') is a species of

cyprinid 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 ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

found only in the coastal streams of southern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

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 shape of the arroyo chub is somewhat chunky, with a deep body and thick, caudal peduncle. The eyes are larger than average for cyprinids. Coloration ranges from silver to gray to olive green above, shading to white below, usually with a dull gray band along each side. The dorsal fin has eight rays, while the rounded anal fin has seven. Males have larger fins than females, and, during the breeding season, patches of breeding tubercles on the upper surfaces of the pectoral fins. This is a small fish, with most adults in the 7–10 cm length range, and a maximum of 12 cm.

Omnivorous 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 ...

, their diet includes

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...

, and

crustacea Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

ns. Studies of fish from warmwater streams shows a preponderance of algae in the stomach (60–80%), and they are also known to feed on the roots of ''

Azolla ''Azolla'' (mosquito fern, duckweed fern, fairy moss, water fern) is a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, looking nothing like other typical ferns but more rese ...

'' (floating water ferns). In cooler streams,

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

s and

caddisfly The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

larvae predominate in the diet. Arroyo chub habitat is primarily the warm streams of the Los Angeles Plain, which are typically muddy torrents during the winter, and clear quiet brooks in the summer, possibly drying up in places. They are found both in slow-moving and fast-moving sections, but generally deeper than 40 cm. They are native to

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...

, Santa Margarita, San Gabriel, San Luis Rey, and

Santa Ana River The Santa Ana River is the largest river entirely within Southern California in the United States. It rises in the San Bernardino Mountains and flows for most of its length through San Bernardino and Riverside Counties, before cutting through ...

s, as well as to Rainbow, Temecula, Malibu and

San Juan Creek San Juan Creek, also called the San Juan River, is a long stream in Orange and Riverside Counties, draining a watershed of .7.5 Minute Quadrangle Map, U.S. Geological Survey, San Juan Capistrano, 1968, photorevised 1981 Its mainstem begins in ...

s. Many of the original populations have been extirpated, but it has recently been reestablished in the

Arroyo Seco (Los Angeles County) The Arroyo Seco, meaning "dry stream" in Spanish, is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. , accessed March 16, 2011 seasonal river, canyon, watershed, and cultural area in Los Angeles County, Cal ...

, a tributary of the Los Angeles River. It has been found in the Los Angeles River (Sepulveda Dam Basin) as recently as 1978. The species also has been successfully introduced in a number of other rivers in the area, and can be found as far north as Chorro Creek in

San Luis Obispo County San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 census, the population was 282,424. The county seat is San Luis Obispo. Junípero Serra founded the Mission ...

, and as far east as the

Mojave River The Mojave River is an intermittent river in the eastern San Bernardino Mountains and the Mojave Desert in San Bernardino County, California, United States. Most of its flow is underground, while its surface channels remain dry most of the time, ...

. The Mojave and

Cuyama River The Cuyama River (Chumash: ''Kuyam'', meaning "Clam") is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 15, 2011 river in southern San Luis Obispo County, northern Santa Barbara ...

populations extend into the ranges of related fishes, and hybridize with Mojave chub and

California roach The California roach (''Hesperoleucus symmetricus'') is a cyprinid fish native to western North America and abundant in the intermittent streams throughout central California. Once considered the sole member of its genus, it has recently been sp ...

, respectively. The species epithet was chosen in honor of

Charles Russell Orcutt Charles Russell Orcutt or C.R. Orcutt (born 27 April 1864 in Hartland, Vermont; died in Haiti 25 August 1929) was a noted naturalist sometimes called "cactus man" because on many expeditions he found new species of cacti. He was active in the San ...

, who made the first collection of this fish in 1889, improvising by using a blanket as a

seine ) , mouth_location = Le Havre/Honfleur , mouth_coordinates = , mouth_elevation = , progression = , river_system = Seine basin , basin_size = , tributaries_left = Yonne, Loing, Eure, Risle , tributarie ...

. It is often misspelled as ''orcutti'', although this is still considered a valid synonym, and is for instance used by Moyle in his book.

References

* * Peter B. Moyle, ''Inland Fishes of California'' (University of California Press, 2002), pp. 130–131 *
Central Arroyo Stream Restoration Program
cf

{{Taxonbar, from=Q969887 Chubs (fish) Gila (fish) Endemic fauna of California Endemic fish of the United States Arroyo chub Fish of the Western United States Freshwater fish of the United States Arroyo chub Arroyo chub Arroyo chub Fish described in 1890