Blacktail shiner facts for kids
Quick facts for kids Blacktail shiner |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Cyprinella
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| Species: |
venusta
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The blacktail shiner (Cyprinella venusta) is a small freshwater fish. It belongs to the Cyprinidae family, which includes minnows and carps. This fish is naturally found in the United States.
Contents
Description and Appearance
The blacktail shiner is a slim minnow. It has 8 or 9 rays on its anal fin (the fin on its belly near the tail). A clear black spot marks the base of its caudal fin (tail fin). Its back is usually yellowish-olive. The sides of its body are silvery with hints of blue. Adult blacktail shiners typically grow to about 100 millimeters (4 inches) long.
The large black spot on its tail helps tell it apart from most other minnows. Sometimes, this spot can be faint, especially in cloudy (turbid) waters. It might be confused with the red shiner (C. lutrensis). However, the red shiner has 9 anal fin rays, while the blacktail shiner usually has 8. Also, the red shiner generally has 35 or fewer scales along its side, but the blacktail shiner has 36 or more.
Where They Live: Geographic Distribution
Blacktail shiners live in areas that drain into the Gulf of Mexico. You can find them from the Suwannee River in Georgia and Florida. Their range extends west to the Rio Grande in Texas. They also live in the Mississippi River basin. This includes areas from southern Illinois down to Louisiana. Westward, they are found in the Red River drainage, reaching western Oklahoma.
These fish are common in the southern United States. They are found west of the Appalachian Mountains. Their range stretches from north-central Florida to West Texas. It also goes north into southern Illinois. In Texas, they are mainly found from the Edwards Plateau eastward. They are not known to live in the Panhandle.
Two different types, or subspecies, of blacktail shiners live in Alabama. The slender blacktail shiner (C. v. stigmaturus) is in the upper Mobile River basin. It is often found above the Fall Line. The eastern blacktail shiner (C. v. cercositgma) lives in the lower Mobile River basin. It also lives in coastal rivers that flow through Alabama. Sometimes, these two types mix in the Alabama, Cahaba, and Tallapoosa river systems.
What They Eat and Where They Live: Ecology and Habitat
Blacktail shiners mostly eat invertebrates, which are small animals without backbones. Their diet also includes algae, seeds, and insects that live in water or on land. In the Blanco River in Texas, aquatic insects and algae were their main foods. Bits of sediment and dead organic matter (detritus) were also found in some fish. Blacktail shiners usually feed during the day. They can be an important food source for piscivorous (fish-eating) spotted bass (Micropterus punctulatus) in the summer. This happens in Village Creek in Texas.
These fish prefer clear, sandy-bottomed rivers. They like pools and runs, which are parts of a river with a steady flow. They are often found where there is not much plant life and the current is strong. However, some populations in higher areas live in creeks. These creeks have more gravel and rubble on the bottom (substrate). In the western parts of their range, they often live in cloudy (turbid) water.
Blacktail shiners can be found in many different river areas. This includes pools, runs, and riffles (shallow, fast-flowing areas). The river bottom can be silt, gravel, or solid rock (bedrock). In the Blanco River, Texas, they were most common in fast-flowing runs during spring and summer. In Village Creek, Texas, they lived in riffle and sandbank habitats all year. During summer, most were found in sandbank areas. Smaller blacktail shiners (less than 17 millimeters or 0.67 inches) were mostly in riffles in fall and winter. Young fish were almost always in sandbank areas during spring.
Blacktail shiners are common in sandy or rocky parts of Lake Texoma (Oklahoma/Texas). They prefer clearer water downstream. They are sometimes plentiful in the tailwaters (water flowing out of a dam). They are rarely found in the headwaters (where a river begins).
Blacktail shiners can sometimes breed with red shiners (C. lutrensis). This mixing of species happens in Texas and Illinois.
Life Cycle and Reproduction
The blacktail shiner can live for up to 4 years in the Leaf River system in Mississippi. In the Blanco River, Texas, they can live up to 5 years.
In Texas, blacktail shiners lay eggs (spawn) from April through September. In Mississippi, spawning happens from late March to early October. Most females are ready to reproduce from April to early September. In Village Creek, Texas, it looked like they had a long spawning season.
Blacktail shiners like to spawn in small cracks or crevices. These are usually found in flowing water. They prefer crevices where the current is about 0.30 meters per second (1 foot per second). Fish living in reservoirs choose crevices in much slower currents. In the Blanco River, Texas, blacktail shiners were seen laying eggs under small rocks and larger cobble stones. This happened in a bedrock riffle with the fastest currents.
Male blacktail shiners react to sounds made by spawning females. They can even tell these sounds apart from those made by female red shiners. Males are territorial, meaning they defend a crevice from other males. A breeding pair swims along the crevice. The female lays her eggs. Usually, the male has already released his sperm into the crevice. So, the eggs are laid into a crevice that already has sperm. Right after spawning, the male turns back and eats any eggs that did not make it into the crevice.
Smaller males, called "sneakers," try to fertilize eggs. They dart between the dominant male and the female as she lays eggs. Both large and small males might enter another male's territory. They will release sperm into a crevice before the dominant male even tries to get a female to lay eggs there.
One study in the Blanco River, Texas, found that female blacktail shiners could have up to 340 eggs (ova). Another study in southwestern Mississippi found that females laid between 139 and 459 eggs at a time. These females were between 48.6 and 72.0 millimeters (1.91 and 2.83 inches) long. The average mature egg was about 1.15 millimeters (0.045 inches) wide. In mature females, their ovaries (where eggs are made) made up 5.8% to 19.1% of their body weight. Females from the Pearl River, Mississippi, laid 20 to 46 batches of eggs during the breeding season. Blacktail shiners become ready to reproduce when they are between 32 and 42 millimeters (1.3 and 1.7 inches) long.
In the Leaf River system, Mississippi, blacktail shiners were about 24 millimeters (0.94 inches) long at age 1. They were about 46 millimeters (1.8 inches) at age 2, and 72 millimeters (2.8 inches) at age 3. Most of the fish in these groups were very young (age 0 and 1). In their first year, blacktail shiners grow to about 45 to 60 millimeters (1.8 to 2.4 inches). In the Blanco River, Texas, they averaged 45 millimeters (1.8 inches) at age 0. They were 66 millimeters (2.6 inches) at age 1, and 90 millimeters (3.5 inches) at age 3 and older.
Conservation and Management
The blacktail shiner is not a major concern for conservation right now. Their numbers are stable. However, there are some issues that could affect them. These include changes to their habitat from flood control projects. Silt (fine dirt) from construction sites can also harm them. Poor water quality and recent water removal for mining and farming are also problems.
Activities like building and running hydroelectric power plants can be a threat. So can flood control, more irrigation, and stabilizing river banks. Oil and gas drilling, mining, and grazing animals near rivers can also cause problems. Introducing or stocking non-native fish might also put the blacktail shiner at risk. Hybridization, where they breed with other fish species, is another possible impact on their population.
See also
In Spanish: Cyprinella venusta para niños
