Pygmy madtom facts for kids
Quick facts for kids Pygmy madtom |
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The pygmy madtom (Noturus stanauli) is a tiny type of fish. It belongs to the Ictaluridae family, which includes catfish. This special fish is only found in two places in Tennessee, United States. Madtoms are the smallest members of the catfish family.
You can recognize pygmy madtoms by their small size. They also have a very long adipose fin (a small, fleshy fin on their back). Their caudal fin (tail fin) is rounded. These fish are usually found in shallow areas with small gravel. They like water that flows at a medium or fast speed, often near the river banks.
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Where Pygmy Madtoms Live
The pygmy madtom lives in very few places. It has only been found in the Duck River in Humphreys and Hickman Counties, Tennessee. It also lives in the Clinch River in Hancock County, Tennessee. These two rivers are about 600 miles apart. We do not know how many places this fish used to live in the past.
What Pygmy Madtoms Are Like
The pygmy madtom is the smallest of all madtoms. It grows to be only about 50 millimeters (2 inches) long when it is an adult. Its back is dark brown, and its belly is almost white.
It looks a bit like the least madtom. But the pygmy madtom has a white snout (nose area). It also has large teeth on the front edge of its pectoral spine (a sharp bone near its front fins). Its tail fin has a dark band or dark spots in the middle. The fin on its belly (anal fin) has 14 to 17 rays (thin bones).
Pygmy Madtom Habitat
Pygmy madtoms have been seen in clear, medium-sized rivers. They like areas with moderate to fast-flowing water and small, pea-sized gravel or fine sand at the bottom.
We do not know if pygmy madtoms move to different habitats during different seasons. However, a close relative, the smoky madtom, moves from fast-flowing areas to shallow pools in winter. Other related species, like the smoky madtom and the yellowfin madtom, live in flowing parts of pools when they are reproducing.
Pygmy Madtom Behavior
It is hard to study the pygmy madtom because it is so rare. Only 10 individuals have been found in total since 1993. This was when the species was listed as endangered.
Scientists at Conservation Fisheries, Inc. in Knoxville, Tennessee, have been able to raise some young pygmy madtoms. They noticed that adult pygmy madtoms are only active in the early evening. This means they are likely crepuscular, which means they are most active at dawn and dusk.
What Pygmy Madtoms Eat
Madtoms mostly eat the larvae (young forms) of aquatic insects. They are "opportunistic feeders." This means they eat whatever small creatures are most common in their habitat.
Pygmy Madtom Reproduction
Related madtoms build nests in small spaces under flat rocks. They sometimes use other objects for cover, like old cans or bottles. Pygmy madtoms live in areas where native mussels are common. So, they might use empty mussel shells for their nests. They probably reproduce from spring to early summer.
Protecting Pygmy Madtoms
The pygmy madtom was listed as an endangered species in 1993. This means it is at high risk of disappearing forever. Because of this, a plan was made in 1994 to help protect it. This plan describes what actions need to be taken and who is responsible.
Challenges for Pygmy Madtoms
The two groups of pygmy madtoms are separated by dams. This means they cannot naturally move between the two rivers. If one group disappears, it cannot be naturally replaced by the other. This also makes it hard for them to share genes, which is important for the long-term health of a species.
Some madtom species have disappeared from parts of their natural homes for unknown reasons. One idea is that they cannot handle pollution in the rivers. This pollution might come from tiny amounts of many different chemicals. Many fish species that once lived all over the Tennessee River now only exist in small, separate groups. Scientists worry that more species will disappear.
Threats to Pygmy Madtoms
Many things threaten the pygmy madtom. These include:
- More cities and towns (urbanization)
- Coal mining
- Accidental spills of toxic chemicals
- Silt (mud and dirt) building up in the water
- Wrong use of pesticides
- Erosion (wearing away) of river banks
- Dredging (digging up) gravel from rivers
- Taking too much water from rivers
- Certain farming practices
None of these threats have gone away since the fish was listed as endangered. Both the Duck and Clinch River groups of pygmy madtoms are still at risk. Laws and rules are in place to protect the fish and its home. However, it is hard to find the fish in surveys. This means we do not fully know how much habitat it needs.
Monitoring Pygmy Madtoms
It is difficult to keep track of the pygmy madtom because it is so rare. Scientists must be very careful when they study them. They need to make sure their methods do not harm the few fish that are left.
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See also
In Spanish: Noturus stanauli para niños
