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.

Bluegill have a deep, flattened body. While their color varies, they are typically olive-green on their back and sides with a yellow to orange belly. A key identifying feature is the dark blue or black “ear” flap on the posterior edge of the gill cover.

Native to eastern North America, from the Great Lakes to the Mississippi River basin, bluegill have been widely introduced throughout the United States and other countries via stocking programs.

They prefer quiet, slow-moving, warm freshwater, such as lakes, ponds, and slow rivers. Bluegill are often found near underwater structures like submerged logs, weed beds, and docks, which provide shade and cover.

Largemouth bass are one of the top recreational fish species in the United States. Many fishing tournaments focusing on largemouth bass are held throughout the country. As a result, they have been stocked throughout the U.S. to provide recreational fishing opportunities. These fish inhabit clear, vegetated lakes, ponds, swamps, and the backwaters of pools, creeks and rivers.

Smallmouth bass are a popular sport fish in the United States. State fish and wildlife agencies conserve smallmouth habitat, install nesting cover in their habitat, stock fish, and regulate harvest. Adult smallmouth bass live in shallow rocky areas of lakes and in the clear and gravel bottom runs and flowing pools of rivers.

Striped bass are often called stripers, linesider or rockfish. They are silvery, shading to olive-green on the back and white on the belly, with seven or eight uninterrupted horizontal stripes on each side of the body. They can live in both freshwater and saltwater environments. Spawning begins in the spring and running water is necessary to keep eggs in motion until hatching. female striped bass can lay up to 3,000,000 eggs and the female will grow larger than the males. 

The channel catfish has been called a swimming tongue. They have taste buds spread over their entire body with most around their gills and whiskers. Channel catfish are a popular recreational fish and are managed by state and tribal recreational fishshing regulations through creel and size limits.

Flathead Catfish (Pylodictis olivaris) is a freshwater fish native to the lower Great Lakes, Mississippi River basin, and parts of the Gulf Slope in the United States and Mexico. Much information is available on P. olivaris, leading to a high certainty of assessment. P. olivaris is a prized sportfish and has been introduced throughout much of the United States. It is also displayed in public aquaria. Impacts of these introductions are well documented and include competition and predation on native fish and invertebrate species, leading to declines in those populations. Several of the native species affected by P. olivaris introduction are federally listed under the Endangered Species Act. History of invasiveness is high. Climate match with the contiguous United States is high overall, with only small regions of low or medium match. Overall risk posed by P. olivaris to the contiguous United States is high.