About Noturus leptacanthus Jordan, 1877
The speckled madtom (Noturus leptacanthus) is dark reddish-brown, with a dusky or mottled caudal fin that has a pale border. The average adult length of this species ranges from 39 to 50 millimetres (1.5 to 2.0 inches), while the longest recorded specimen reached 110 millimetres (4.3 inches).
This fish has a wide distribution across the southeastern United States. It is abundant in Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, and Tennessee. In Tennessee, it is found only in the Conasauga River system, where it remains abundant. Its range also covers Atlantic and Gulf slope drainages, extending from the Edisto River in South Carolina to the Amite-Comite River system of Louisiana. The southernmost extent of its range is the St. Johns River system in the Florida peninsula.
The speckled madtom lives in small to moderate-sized streams. It often occupies very shallow riffles with sand, rock, or gravel bottoms. During the day, it rests in areas with aquatic vegetation including pondweed and burweed. It has nocturnal feeding habits, so it leaves these resting areas to feed at night. Feeding starts at dusk, and the amount of food in its stomach increases until dawn, when feeding stops. Its diet consists mostly of insect larvae, particularly midge larvae. It detects food using its sensory barbels, and vision plays very little role in its feeding behavior.
Major competition for the speckled madtom comes from other species in the genus Noturus. The only known predators of this species are rock bass (Ambloplites rupestris) and larger Noturus species. All Noturus species have a venomous sting delivered through their pectoral spines to defend against predation, but the speckled madtom has a relatively low level of venom toxicity.
