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The pygmy madtom (Noturus stanauli), is a type of catfish (family
Ictaluridae), a family of fish easily recognized by whiskerlike barbels
extending from their upper jaw. The pygmy madtom is the smallest madtom
species known. Adults are less than 2 inches (50 millimeters) long.
Described in 1980 by David Etnier and Robert Jenkins, the pygmy madtom is
dark brown dorsally (on its back from nose to tail and down its sides),
while its belly is nearly white.
The pygmy madtom is known only from two short stream reaches in the lower
Duck (Hickman and Humphries Counties) and middle Clinch (Hancock County)
Rivers in the Tennessee River system, Tennessee. These sites are separated
by 650 miles of mostly impounded Tennessee River habitat.
| The pygmy madtom is a federally endangered species,
listed in 1993 because of threats it faced from water quality
deterioration and pollution, its restricted geographic range, and its
resulting vulnerability to catastrophic events such as a chemical
spill. |
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One of the rarest fishes in North America, about 25 museum specimens of
pygmy madtom are known, and only about 50 specimens have ever been
collected. Approximately one in two collecting efforts produces any pygmy
madtoms in the Clinch River; and one in four efforts produces them in the
Duck River The last pygmy madtoms collected in the Duck were sampled in
1993.
Pygmy madtoms inhabit shoal areas of medium-sized rivers with gravel
substrates, from 8 to 40 inches (0.6 to 3.3 feet) deep, and with currents of
13 to 27 inches (1.1 to 2.3 feet) per second. They’ve generally been
collected near stream banks. The most imperiled madtom species tend to
inhabit the best remaining stream reaches in terms of habitat quality (e.g.,
relatively silt-free, stable substrates, high water quality).
A highly diverse number of fish species are associated with pygmy madtom
habitat. The Duck River in the vicinity of pygmy madtom habitat supports
over 90 species. The Clinch River harbors about 80 fish species and has the
highest number of federally listed mussels (18 species) of any stream in the
world.
Very little is known about pygmy madtom life history. Indications are
that they live 1 + years. In captivity, a pair of pygmy madtoms collected in
March 2000, spawned (deposited eggs) twice, once in late June/early July,
the second time in late July. Clutch size (the number of eggs produced at
one time) varied from 10 in the first spawn to 19 eggs in the second. The
male guards the nest, which occupies a cavity under a rock or similar
shelter. Food appears to be aquatic insect larvae. Madtoms are generally
thought to be nocturnal, however, there is evidence from laboratory
observations that they may be crepuscular. |
