The mullets or grey mullets are a family (Mugilidae) of ray-finned fish found worldwide in coastal temperate and tropical waters, and in some species in fresh water like the Shingle Fish. Mullets have served as an important source of food in Mediterranean Europe since Roman times. The family includes about 80 species in 17 genera, although half of the species are in just two genera (Liza and Mugil).
Mullets are distinguished by the presence of two separate dorsal fins, small triangular mouths, and the absence of a lateral line organ. They feed on detritus, and most species have unusually muscular stomachs and a complex pharynx to help in digestion.
Taxonomically, the family is usually treated as the sole member of the order Mugiliformes, but as Nelson says, "there has been much disagreement concerning the relationships" of this family. The presence of fin spines clearly indicates membership in the superorder Acanthopterygii, and in the 1960s they were classed as primitive perciforms, while others have grouped them in Atheriniformes. FishBase follows William A. Gosline in placing the family in the Perciformes.
In North America, "mullet" by itself usually refers to Mugilidae. In Europe, the word "mullet" is usually qualified, the "grey mullets" being Mugilidae and the "red mullets" or "surmullets" being Mullidae, notably members of the genus Mullus, the red mullets. Outside Europe, the Mullidae are often called "goatfish". Fish with common names including the word "mullet" may be a member of one family or the other, or even unrelated such as the freshwater white sucker (Catostomus commersonii). In Hawai'i the mullet (Mugil cephalus) is referred to as "'ama'ama".