Least darter facts for kids
Quick facts for kids Least darter |
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The least darter (Etheostoma microperca) is a tiny freshwater fish. It belongs to a group of fish called darters. These fish are part of the larger family that includes perches. You can usually find least darters in lakes and streams. They live in the northeastern United States and near the Mississippi River system.
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About the Least Darter
Least darters are very small fish. They are usually about 25 to 35 millimeters (1 to 1.4 inches) long. The biggest ones are about 45 millimeters (1.8 inches). Their bodies are light olive brown with darker brown spots.
They often have a short or missing "lateral line." This is a special line of sensors that helps fish feel vibrations in the water. They also have 7 to 15 dark blotches on their sides. These blotches are wider than they are tall.
Their second dorsal fin and tail fin have small dark spots. These spots form wavy lines. Least darters also have a clear tear-shaped spot under each eye. Other dark lines often spread out from their eyes onto their heads.
When males are ready to breed, they get a band of red spots. This band is in the middle of their first dorsal fin. Their pelvic, pectoral, and anal fins also turn orange or red. Females look much like males. However, they do not have the red or orange colors. Their pelvic fins are also smaller.
These fish have a body shape that is slightly long and round. Their scales have tiny tooth-like bumps. This helps them move through the water. They have 32 to 38 of these special scales. Their fins are rounded or squared.
Least darters have two dorsal fins. The first one has 5 to 7 spines. The second has 9 to 10 soft rays. Their pectoral fins are important for moving up and down. They also help the fish steer at slow speeds. These fins can even help them stop or stay in place in strong currents. This is because least darters do not have a swim bladder. A swim bladder usually helps fish float.
Where Least Darters Live
The least darter, Etheostoma microperca, lives in the northeastern United States. They are common in the Midwest. This fish is one of many species found in Tennessee. It has also been seen in states like Minnesota, Illinois, and Ohio.
In Minnesota, they were found in a few places as of 2008. Most of these groups lived in the Otter Tail River and upper Mississippi River areas.
Adult least darters usually live in streams. They like areas with lots of plants. This includes grassy banks that hang over the water. They also like areas with stringy algae. Young darters mostly live in thick algae patches. These patches are along the edges of streams.
These fish rarely swim in the middle of streams. They stay close to the edges where the water is calmer. This helps them avoid strong currents. They prefer natural lakes and wetlands that always have water. These places must also have clear water and many aquatic plants.
What Least Darters Eat
Least darters are good at finding food on and around plants. Their mouth opens forward. This helps them grab prey that is in front of them. Their long body and fins help them catch food quickly.
They mostly eat small insects. These include certain types of fly larvae and nymphs. Very tiny creatures are also important parts of their diet. These include small crustaceans and other insect larvae. Since least darters are small, they eat very small prey.
Life Cycle of the Least Darter
Least darters move from deeper stream pools to shallow, weedy areas. This happens from March to May. This is when they get ready to lay eggs.
During this time, male darters claim small areas. These areas are about 30 centimeters (12 inches) wide. They protect these spots from other males. Females then swim into a male's area. They lay their eggs on water plants. A female can visit many males' areas. She can lay about 30 eggs each day.
Least darters do not live very long. In Minnesota, they usually live for 2 to 3 years.
By early January, the males start to get ready for breeding. Their bodies change, and by March or April, they are ready to mate. They also get special skin flaps on their fins. Their breeding colors become bright by mid-March. Females also show changes, but their colors do not change much.
Least darters almost always lay their eggs while standing upright. Sometimes, they lay eggs while in a horizontal position. Males often mate with several females. Males also guard their small areas. They protect the eggs until they hatch.
Protecting Least Darters
Losing or damaging their homes is the biggest danger to least darter populations. They are easily harmed by pollution and pesticides. Runoff from farms and cities also hurts them. Too many nutrients in the water (eutrophication) is also a problem. They also suffer when their special habitats are lost. These habitats include calm waters and aquatic plants.
Other dangers include losing forests around streams. Stream restoration projects can also be a problem. Introducing fish that are not native or that eat darters is also a threat. To help this species, we need to keep water systems clean and healthy. Areas with many least darters should be protected. They need to be safe from human activities and building projects.
Conservation Efforts in Minnesota
Before 1990, least darters were found in 31 places in Minnesota. These included 10 streams and 9 lakes. From 1990 to 2002, 47 new places were found. These were in 9 new streams and 41 new lakes. Most of these new spots were in the Otter Tail River system. They were also found in the upper Mississippi River area.
One discovery was in Long Lake. This was the first time least darters were found in the Lake Superior area. Surveys from 1997 to 2008 found new places for this fish. But they also found that some old places were lost. This happened in areas with a lot of development.
We need more detailed studies to know how many least darters there are. We also need to find out what specific things are harming them. This will help us protect them better. Studying their genes might also help save this rare fish. Right now, there are no specific plans just for least darters in Minnesota.
