Madtom

Madtoms are freshwater catfishes (order Siluriformes) of the genus Noturus of the family Ictaluridae. It is the most species-rich family of catfish in North America, native to central and eastern United States, and adjacent parts of Canada. Their fin spines contain a mild venom with a sting comparable to that of a honey bee.

Nearly half the species of madtom catfishes was described in a single comprehensive revision of the group. Morphology is very conserved in this genus; most of the species look very similar and it is difficult to tell them apart with the usual meristic and morphometric characters used to identify species. The more conspicuously variable attributes of these secretive fishes are features of pigmentation, which also are more difficult to quantify and often vary according to substrate and water quality. These species have small to tiny or fragmented ranges, and aspects of pigmentation are important diagnostic characters of each. Over one quarter of the recognized species diversity in Noturus remains undescribed.