The freckled madtom looks similar to the tadpole madtom and shares much of its range, but its upper jaw projects beyond the lower jaw, and the underside of the head and body are sprinkled with dark speckles.
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 freckled madtom can be distinguished by the following characters:
- The upper jaw projects beyond the lower jaw.
- The underside of the head and body, including the lower lip and chin, is sprinkled with dark speckles.
- Apart from the dark speckles, the body and fins are plain, without definite blotches, bars, or saddle marks.
- The midside lacks a prominent veinlike dark line.
- The notch between the adipose fin and the tail fin is closer to the tip of the tail fin than to the dorsal fin base.
- The pectoral spine lacks sawlike teeth on the rear margin. ----The tooth pad on the upper jaw lacks backward extensions.
Like the tadpole madtom, the freckled madtom has back and sides uniformly light tan or chocolate brown and the belly white or pale yellow. The fins are similar in color to nearby parts of the body. The major difference in coloration is the freckled madtom’s dark speckles.
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: Missouri has three other madtoms whose bodies are rather uniformly colored and lack distinct dark blotches, bars, or saddle marks: The slender and tadpole madtoms (N. exilis and N. gyrinus), and the stonecat (N. flavus). The slender and tadpole madtoms have the upper and lower jaws about equal (the upper jaw does not overhang the lower jaw). The stonecat shares with the freckled madtom the “overbite,” but it has backward extensions on the teeth pad of the upper jaw, plus its lower lip and chin lack dark pigment.
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.
Habitat and Conservation
The distribution of the freckled madtom is similar to that of the tadpole madtom (southeast Missouri, and the creeks and backwaters of the Missouri and Mississippi rivers), but it unlike the tadpole madtom it is typically found in riffles or in portions of the stream that have gravel or rocky bottoms.
The freckled madtom occurs widely in the Bootheel lowlands and nearby sections of the Ozarks, as well as the prairie streams of central and northeastern Missouri. It is seldom found in large numbers. The most substantial populations are in the upper Osage and Marmaton rivers, the upper Mississippi River, and in a few dictions of the southeastern lowlands.
This madtom is primarily an inhabitant of large, clear to moderately turbid rivers having permanent strong flow and low or moderate gradients. It occurs on riffles over bottoms of sand and gravel, often mixed with considerable quantities of detritus.
Although madtoms are not useful to people as food or game, they are interesting animals that contribute to the diversity and health of the aquatic ecosystems they inhabit.
Aquarists understand the fascination of small fishes. Madtoms can make good aquarium subjects, although they tend to remain hidden. They usually can be coaxed into the open with food, especially under low illumination at night, when they are normally active. A benefit of madtoms is that they do not outgrow a tank the way our other native catfish do. Nongame fishes that are not otherwise protected may be collected for aquarium purposes by the holder of a fishing permit, using techniques and in numbers specified for bait collecting in the Wildlife Code of Missouri.
By feeding on immature midges and mayflies, this madtom serves as a check on the populations of those insects. The presence of stout, venomous spines reminds us that many animals seek out the freckled madtom as prey.
Madtoms are part of the complex web of feeding relationships that occur in streams. Though small, madtoms are often abundant in streams, and their populations represent a significant link in the food chain.