The bonytail is the rarest of the endangered, native fish of the Colorado River and is thought to have evolved around 3 to 5 million years ago. Its name describes the fish as an elegant swimmer and member of the chub group of minnows.
Bonytail were once common in portions of the upper and lower Colorado River basins. In the early 1900s, Chuck Mack of Craig, Colorado, called them broomtails, because “…you could get a firm grip on their bony tail.” Mack, and other old-timers, used to catch these fish in the upper Colorado River basin, along with Colorado pikeminnow and razorback sucker.
Recovery efforts for this species are ongoing, with stocking occurring at multiple locations in both the upper and lower Colorado River basins. Threats to the species include streamflow regulation, habitat modification, competition with and predation by non-native species and hybridization.
The bonytail is a member of the genus Gila and is closely related to the humpback chub (Gila cypha) and roundtail chub (Gila robusta). The three species co-occur in habitats in the Colorado River Basin and have substantial evidence of hybridization but maintain species-specific characteristics and populations.
Bonytail may attain weights of two pounds (about 1.1 kilograms).
This species has a gray or olive-colored back, silver sides and a white belly.
The bonytail is a member of the minnow family. They have large fins and a streamlined body that is pencil-thin near its tail, enabling it to swim in swift rivers.
Length: May reach 22 in (about 550 mm)
It is hypothesized, based on available distribution data, that flooded bottomland habitats are important growth and conditioning areas for bonytail, particularly as nursery habitats for young.
Bonytail have been known to live to 50 years of age.
Like other closely related Gila species, bonytail in rivers probably spawn in spring over rocky substrates; spawning in reservoirs has been observed over rocky shoals and shorelines. Spawning has also been confirmed in off-channel floodplain wetlands.
Little is known about the specific habitat requirements of bonytail because the species was extirpated from most of its historic range prior to extensive fishery surveys. The bonytail is considered adapted to mainstem rivers where it has been observed in pools and eddies.
A natural body of running water.
Bonytail eat a variety of foods, including insects, crustaceans, plants and seeds. They also occasionally eat small fish and reptiles.
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