While visiting Southern Illinois last October, I found a few examples of a neat fish that I had never encountered before. A tiny catfish, an adult Tadpole madtom is typically 2–3 inches long – however they have been recorded to reach a length of 5 inches.
This species lives in the pools and backwaters of sluggish creeks and rivers, as well as in shallow areas of lakes. It avoids fast rocky streams and usually is found near rocks or debris over a soft substrate. Its range includes most of the eastern United States.
These catfish, as well as the other Madtoms, can inflict a painful puncture wound with the spines on their pectoral and dorsal fins. When one is stung or pricked by one of the spines, there is a burning sensation similar to a bee or wasp sting.
Like many catfish species, Madtoms have venom glands at the base of these fins. The glands secrete venom that becomes incorporated in the slime and cells that make up the spine. This is a useful defense mechanism to keep it from being eaten by predators.
Like others in its family, it is nocturnal and relies on its sensory “whiskers” (called barbels) to find its favorite foods. The Tadpole Madtom feeds on insects and other invertebrates, as well as occasionally consuming algae and aquatic plants.
It was a really neat experience to meet this very cool fish while visiting the “Land of Lincoln.”