The bonytail chub or bonytail, Gila elegans, is an endangered cyprinid freshwater fish native to parts of Arizona, California, Colorado, Nevada and Utah in the United States. It is the rarest of the endemic big-river fishes of the Colorado River. The bonytail chub has never been valued as a sport or food fish.
The bonytail chub can grow to over 2 feet (60 cm) long. Like many other desert fishes, its coloring tends to be darker above and lighter below, serving as a camouflage. Breeding males have red fin bases. They have a streamlined body and a terminal mouth.
The bonytail chub was once found in many states, including Arizona, California, Colorado, New Mexico, Utah, and Wyoming. This fish species experienced the most abrupt decline of any of the long-lived fishes native to the main-stems of the Colorado River system and, because no young individuals have been found in recent years, has been called functionally extinct. Bonytail chubs were one of the first fish species to reflect the changes that occurred in the Colorado River basin after the construction of Hoover Dam; the fish was extirpated from the lower basin between 1926 and 1950. They may still be found in the Green River of Utah and perhaps in the larger Colorado River water bodies. Gila elegans was added to the US list of endangered species on April 23, 1980. The species has been re-introduced to parts of its native range from captive stocks.
There is contention about the reintroduction of the bonytail chub. Some are concerned about the amount of water used to increase stream flows that are required for adequate bonytail chub habitat. Bass fishermen are concerned about facilitating the recovery of the bonytail chub by the removal of smallmouth bass, a popular gamefish. Fears of spreading the quagga mussel, an invasive species that clogs water pipelines and fouls marine equipment, has halted the reintroduction of the bonytail chub in Arizona, pending establishment of a stocking protocol that is satisfactory to Arizona wildlife officials.
Bonytail chub prefer backwaters with rocky or muddy bottoms and flowing pools, although they have been reported in swiftly moving water. They are mostly restricted to rocky canyons today, but were historically abundant in the wide downstream sections of rivers.
Young bonytail chubs typically eat aquatic plants, while adults feed mostly on small fish, algae, plant debris, and terrestrial insects. Little is known about their reproductive habits, but they are thought to spawn in mid-summer and perhaps hybridize with both Colorado and humpback chubs.