The morphology of the razorback sucker is distinguishable from all other catostomids by the dorsal keel rising posterior from the head.
Razorback sucker are robust in size and slightly compressed laterally.
The upper body is dark brown to olivaceous and white or yellow on the lower ventro-lateral surfaces. During the spawning season males often have a lighter coloration and have well developed tubercles on the anal and caudal fins. Mature females are, on average, larger than males in both the Upper and Lower Colorado River Basin populations. The razorback sucker is endemic to the Colorado River drainage. In the Lower Basin, razorback sucker are found primarily in large Colorado River impoundments including Lake Mohave, Lake Meade and Lake Havasu.