Mountain Madtom

Noturus eleutherus

Mountain_Madtom_Noturus_eleutherus_10-20-13.jpg

Mountain madtom side view photo with black background
Mountain madtom, Noturus eleutherus
Lance Merry
Endangered
Species of Conservation Concern
Family

Ictaluridae (bullhead catfishes) in the order Siluriformes (catfishes)

Description

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.

Size

Adult length: about 2¼–3½ inches; maximum about 4 inches.

Habitat and conservation

You are unlikely to come across the mountain madtom in Missouri. It has a very limited distribution in our state. It has only been collected at four locations in southeast Missouri, including 18 specimens collected from the Black and St. Francis rivers, and the Current River near the Arkansas state line.

In Missouri the mountain madtom is known only from large, moderately clear rivers in or near the transition zone between Ozark and Lowland regions. It occurs in gravelly riffles, sometimes where there are thick growths of aquatic vegetation. It typically hides under flat rocks during the day.

It is sensitive to siltation and does not live in places with muddy or sandy substrate. The eggs, in particular, are sensitive to silt: when silt settles on mountain madtom eggs, the eggs will suffocate. Farming, logging, and other soil disturbances can cause increased amounts of silt to enter streams and thus degrade the aquatic habitats this species requires.

Because this species requires streams with fast-flowing water, dam construction has reduced the amount of potential habitat.

Foods

Mountain madtoms feed intensely, in relatively short bursts, only at night, and mostly during the first four hours after sunset. They forage among rocks and rooted vegetation, chiefly in riffle areas, for immature aquatic insects, including mayflies, caddisflies, stoneflies, and various members of the family of true flies.

image of Mountain Madtom distribution map
Distribution in Missouri

Recorded in our state from only a few locations in the southeastern quarter: the Black River near Poplar Bluff, the St. Francis River near Sam Baker State Park, and the Current River near the Arkansas state line.

Status

State Endangered; a Species of Conservation Concern in Missouri. This fish is more common east of the Mississippi River. Habitat degradation resulting from human land use near streams jeopardizes the populations in our state. Siltation, sedimentation, and pollutants seeping from nearby lands degrade the aquatic habitat mountain madtoms require.

Life cycle

In our state, mountain madtoms probably spawn in May and June, depositing eggs beneath rocks in shallow, shaded pools having a floor of clean-swept fine gravel. As with most catfish, there is parental care: males guard the eggs and continue to watch over the larvae for a few days after hatching. Mountain madtoms can live for up to 4 or 5 years, with males living longer and attaining greater lengths than females.

Human connections

Missourians can be proud of our state for many reasons. One bragging point we have over most of the neighboring states is the richness of our fish community, including rare types like this madtom. There are more than 200 kinds of fish in our state. Kansas, for example, only has about 140.

Although most of Missouri’s species of madtoms may be collected and kept as aquarium fish (if you have a valid Missouri fishing permit; see the Wildlife Code of Missouri for details), you cannot collect or possess endangered or threatened species, including the mountain madtom and Neosho madtom.

The two parts of the scientific name are somewhat contradictory. The genus name, Noturus, means “back tail” and refers to the connection between the adipose fin and the tail that characterizes the madtoms as a group. But the species name, eleutherus, means “free” and refers to the almost complete separation of the same two fins in this particular species.

Ecosystem connections

Like many fish of its size, this madtom plays an intermediate role in the food chain: It preys on smaller creatures but is preyed upon by larger animals. Like other madtoms, this species has a mild venom in its pectoral and dorsal spines that helps protect it from predation.

Non-point-source pollution is an important concept to understand. It’s easy to see how dumping a pollutant right into a stream can degrade water quality, but it’s a little harder to grasp how oil, detergent, salt, fertilizer, or pesticide applied to land that seems far from a stream is ultimately washed into our waterways. It’s also harder to see how construction or other soil disturbance on “dry land” can lead to siltation in nearby streams. Fortunately, people can learn these principles and take care to prevent our streams from being degraded.