The Gonorynchiformes are an order of ray-finned fish that includes the important food source, the milkfish (Chanos chanos, family Chanidae), and a number of lesser-known types, both marine and freshwater. The alternate spelling "Gonorhynchiformes", with an "h", is frequently seen but not official. Gonorynchiformes have small mouths and no teeth. They are the sole group in the clade Anotophysi, a subgroup of the superorder Ostariophysi. They are characterized by a primitive Weberian apparatus formed by the first three vertebrae and one or more cephalic ribs within the head. This apparatus is believed to be a hearing organ, and is found in a more advanced and complex form in the related cypriniform fish, such as carp. Also like the cypriniforms, the gonorynchiforms produce a substance from their skin when injured that dissolves into the water and acts an alarm signal to other fish.

Taxonomy

Although many of the families are rather small, there are several fossil genera. This listing of the groups of Gonorynchiformes includes fossil fish with a short description. They are listed in approximate order of how primitive their characteristics are. The 5th edition of Fishes of the World classifies the extant taxa in this order as follows, as does Eschmeyer's Catalog of Fishes: Order Gonorynchiformes Greenwood, Rosen, Weitzman, and Myers, 1966

Timeline of genera