The clade Otocephala includes the Clupeiformes (herrings) and Ostariophysi (carps, catfishes and allies). All three major bullheads can be confused with other catfishes by novice anglers. Pterygoplichthys or commonly known as Janitor fish is a genus of South American armored catfishes. Vandellia is a genus of catfishes native to South America. Chrysichthys is a genus of claroteid catfishes native to Africa. Madtoms are freshwater catfishes (order Siluriformes) of the genus "Noturus" of the family Ictaluridae. Typical examples are the electric eel, the electric catfishes, and electric rays. Bagrus is a genus of bagrid catfishes. Clarias is a genus of catfishes (order Siluriformes) of the family Clariidae, the airbreathing catfishes. This occurs in North American freshwater catfishes, many butterflyfishes, sea horses and several other species. Ameiurus is a genus of catfishes in the family Ictaluridae. Marine catfishes, sea horses and grunts stridulate by rubbing together skeletal parts, teeth or spines. "Pseudoplatystoma" species are all large, boldly striped or spotted catfishes. Like many other catfishes, females are larger than males in this species. Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes.