18 inches long and one pound

Like the other native fish of the Colorado River, the bonytail chub is distinctively adapted to the Colorado River. Its sleek body and a rounded keel on its back, just behind the head allows it to negotiate the fast and turbulent water of the big, muddy violent currents that existed in the river prior to the construction of major hydroelectric dams along the river corridor. It has small scales and a relatively smooth body, small mouth on the front of its head, and elongated fins. Its body narrows to a thin notch at the base of its tail and it has a deeply notched caudal fin.

Up to 50 years

Historic habitat was the turbid waters and quiet, muddy backwaters of the Colorado River system.

Historic range for the bonytail chub was a major portion of the Colorado River. Their present range is restricted to Lake Mojave.

Specific adaptations allowed the bonytail chub to thrive in the sometimes violent, sometimes bleak flows of the wild rivers of the west. As annual floods brought silt into the slow bends of the rivers, it deposited long spits of sand. These created backwaters with limited flows and cloudy water that provided perfect nesting and nursery habitat. Once the fry reached viable size, off they went to join other native fish in the mainstream of the river.

Bonytail chub feast on the mircoinvertibrates in the river.

Like other chubs, the bonytail chub is a prolific breeder. It scatters its eggs along a calm stretch of river bottom. As the eggs hatch, they make their way to a nearby backwater nursery, until they reach a viable size.

Endangered

The first major decline in populations was noted in 1941, throughout the entire river system. Construction of dams flooded some of the habitat and cleared up the tailrace water, robbing it of the silt, which built the protective backwaters. Game fish and other non-native fish were introduced, which compete with native fish and prey on the fry. None of the natural fry ever made it to adulthood. The last bonytail chub ever taken from its natural river habitat was in 1985.

Stocking and reintroduction efforts have proven fairly unsuccessful, because of predation on the small stocked fish. Isolated populations have been successfully reared to adult stage in pools cleared of other fish. But, these are small populations and not connected with the last viable group in Lake Mojave, so chances of total population survival by this method are bleak. New methods of rearing and stocking adult fish are being tried and hold some potential for maintaining existing populations. But, without their critical habitat, the future is not bright for a full recovery.

Like the other native fish of the Colorado River, the bonytail chub is a holdover from prehistoric times, a living fossil. For the first 10,000 years of human existence, the razorback sucker had a longer average life span than a homo sapien.