Noturus gyrinus (Mitchill 1817)
Identification: The body and fins of the Tadpole Madtom are uniformly light tan or brown with a dark gray veinlike line along the middle of the side. It has a stout body and a terminal mouth with equal jaws (neither jaw protrudes in front of the other). The pectoral spine lacks sawlike teeth on its rear edge. The caudal fin is rounded on the adult but often is more pointed on a juvenile. There are 13-18 anal rays. To 5 in. (13 cm) total length.
Range: The Tadpole Madtom is found in Atlantic and Gulf Slope drainages from New Hampshire to the Nueces River in Texas and in the St. Lawrence-Great Lakes, Hudson Bay (Red River), and Mississippi River basins from southern Quebec to southern Saskatchewan, and south to the Gulf of Mexico. The species has been introduced into the Snake River in Idaho and Oregon and may have been introduced into Massachusetts and New Hampshire. It is common over most of its range but avoids high-gradient streams and thus is absent from the Appalachian and Ozark Highlands.
Habitat: The Tadpole Madtom lives in pools and backwaters of sluggish creeks and small to large rivers, and in shallow areas of lakes. It avoids fast rocky streams and usually is found near rocks or debris over a soft substrate.
Similar species: The Ouachita Madtom, Noturus lachneri, has a shorter and flatter head and a more slender body. The Broadtail Madtom, an undescribed species of Noturus, has an upper jaw that projects beyond the lower jaw. The Speckled Madtom, Noturus leptacanthus, has dark spots on the body and fins and a caudal fin with a straight edge.