The mountain madtom is rare and endangered in Missouri. This small catfish has been recorded from only a few locations in the southeastern quarter of the state.
Madtoms, as a group, are small, secretive catfishes that most people never see. The key identifier for madtoms has to do with the adipose fin (the small, fleshy fin that is present on the midline of the back just ahead of the tail fin). In madtoms, the adipose fin forms a low, keel-like ridge without a free, flaplike lobe along the trailing edge. The adipose may be connected to the tail fin, or it may have (at most) a slight notch in between. (In our other catfishes, the adipose fin forms a free, flaplike lobe, widely separate from the tail fin.)
The mountain madtom can be distinguished from our other madtoms by the following: The dark bar at the base of the adipose fin does not extend to near the fin margin. The pectoral spine has small, sawlike teeth well-developed along the front margin. The body and fins are profusely mottled with brownish blotches and bars. The upper jaw projects beyond the lower jaw. There is no dark bar across the middle of the tail fin, and no dark line across the base of the tail fin. The head length goes fewer than 3.5 times into the standard length.
Most madtoms possess a mild venom that is associated with the pectoral and dorsal spines. When introduced into a puncture wound produced by the spine, the venom causes a painful reaction. The spines are often erected and locked in place when the madtom is alarmed, increasing the chance of a puncture. The venom is not considered dangerous to people, and the chances of being “spined” are not great if the possibility is kept in mind when handling a madtom. If you’ve been jabbed by a madtom spine and think you’re having a severe reaction, seek medical attention.
Similar species: The brindled and Neosho madtoms are most similar.
- The brindled madtom (N. miurus) has the dark bar or blotch at the base of the adipose fin extend upward to quite near the fin margin; also, it often has a narrow, dark line shaped like a question mark along the base of the tail fin, which the mountain madtom never has.
- The Neosho madtom (N. placidus) has a dark crescent-shaped bar across the middle of the tail fin, and it has small sawlike teeth only poorly developed on the front margin of the pectoral fin spine. Also, the Neosho madtom is a very rare fish only known in Missouri from southwest part of the state (the Spring River in Jasper County).
There are about 30 species of madtoms (in the genus Noturus), and all occur in the central and eastern United States and nearby parts of Canada. In Missouri, 10 species of madtoms have been recorded. It can be difficult to separate the different species of madtoms using the traditional methods of fish ID (counting fin rays, for instance, or comparing ratios of body-part measurements). Noting differences in pigmentation (such as dark bars or patches) can help, but such coloration often varies by particular locality and habitat (such as amount of vegetation, turbidity, or different substrates). Color can also vary by a fish’s health, mood, breeding condition, sex, and individual genetics, and dead fish may show little coloration at all. Molecular (DNA) date is being used more and more as a way to separate the species; of course, it is not very useful in the field. Geography can be a good clue for species IDs, since different species may be restricted to certain stream systems and never occur in others.