Cypriniformes is an order of ray-finned fish, which includes many families and genera of cyprinid (carps and their kin) fish, such as barbs, gobies, loaches, botias, and minnows (among others). 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 (with some authorities having listed as many as 23),[1] over 400 genera, and more than 4,250 named species; new species are regularly described, and new genera are recognized frequently.[2] Cyprinids are most diverse in South and Southeast Asia, but are entirely absent from Australia and South America.[3] At 112 years old, the longest-lived cypriniform fish documented is the bigmouth buffalo.[4]
Their closest living relatives are the Characiformes (characins, tetras and their kin), the Gymnotiformes (electric eel and American knifefishes), and the Siluriformes (catfishes).[5]
Like other orders of the Ostariophysi, fishes of Cypriniformes possess a Weberian apparatus. They differ from most of their relatives in having only a dorsal fin on their backs; most other fishes of Ostariophysi have a small, fleshy adipose fin behind the dorsal fin. Other differences are the Cypriniformes' unique kinethmoid, a small median bone in the snout, and the lack of teeth in the mouth. Instead, they have convergent structures called pharyngeal teeth in the throat. While other groups of fish, such as cichlids, also possess pharyngeal teeth, the cypriniformes' teeth grind against a chewing pad on the base of the skull, rather than an upper pharyngeal jaw.
The most notable family placed here is the Cyprinidae (carps and minnows), which make up two-thirds of the order's diversity. This is one of the largest families of fish, and is widely distributed across Africa, Eurasia, and North America. Most species are strictly freshwater inhabitants, but some are found in brackish water, such as roach and bream. At least one species is found in saltwater, the Pacific redfin, Tribolodon brandtii.[6]