The Catostomidae are the suckers of the order Cypriniformes, with about 78 species in this family of freshwater fishes. The Catostomidae are almost exclusively native to North America. The only exceptions are Catostomus catostomus, found in both North America and Russia, and Myxocyprinus asiaticus found only in China. In the Ozarks they are a common food fish and a festival is held each year to celebrate them. The bigmouth buffalo, Ictiobus cyprinellus, can reach an age up to 127 years, making it the oldest known freshwater teleost by more than 50 years.

Cypriniformes is an order of ray-finned fish, which includes many families and genera of cyprinid fish, such as barbs, gobies, loaches, botias, and minnows. Cypriniformes is an “order-within-an-order”, placed under the superorder Ostariophysi—which is also made up of cyprinid, ostariophysin fishes. The order contains 11-12 families, over 400 genera, and more than 4,250 named species; new species are regularly described, and new genera are recognized frequently. Cyprinids are most diverse in South and Southeast Asia, but are entirely absent from Australia and South America. At 112 years old, the longest-lived cypriniform fish documented is the bigmouth buffalo.