The tadpole madtom (Noturus gyrinus), also called the willow cat, is in the family Ictaluridae—the fish family that contains catfish. Its range includes most of the eastern United States, where it lives in slow-water areas such as pools and backwaters of creeks, small to large rivers, and shallow areas of lakes.
Like other catfish, the tadpole madtom is nocturnal and relies on its sensory “whiskers” (called barbels) to find its favorite foods—insects, plankton, and particulate matter—while perusing the bottom substrate.
The tadpole madtom is a small fish—typically 2–3 inches—however, it has been reported to reach 5 inches. It has a dark brown back with a lighter brown color on its sides and a yellow or white underside. It’s distinguished from bullheads and larger catfish species by having an adipose fin fused to its large, round caudal fin.
The tadpole madtom has a stout body and a terminal mouth with jaws that line up equally. The jaws of madtoms can be a key feature to look at when identifying different madtom species. For example, the freckled madtom’s upper jaw projects beyond the lower jaw.
Perhaps the most well-known characteristic of the tadpole madtom is its venomous spines! The spines—located on its sides and back—are a great defense because the venom can incapacitate a predator for up to a few hours. The venom’s effect on humans is often compared to the feeling of a bee sting.
The tadpole madtom’s spines also increase the fish’s size when they are erected, which can make the fish too large for some smaller predators to swallow, or at least make it harder for the fish to be consumed.
Despite these defense mechanisms, the tadpole madtom is sometimes used as bait for walleye, sauger, and/or other sport fish. It is legal to possess 6 of the 7 madtom species found in Illinois. The exception is the northern madtom, which is an endangered species in Illinois. The northern madtom is only found in Illinois’ east central and southeast counties. Its body is yellow or tan with dark mottling, its underside is white to yellow, and it has a protruding upper lip like the freckled madtom.
So if you plan on using madtoms as bait, make sure you can easily distinguish them from the state-endangered northern madtom so that you don’t harm its population. Also remember to take caution when handling these small kitties because they can pack an unpleasant sting!