Smallmouth yellowfish facts for kids

{{Speciesbox | image = Labeobarbus aeneus, Orange river, Richtersveld.jpg | status = LC | status_system = IUCN3.1 | status_ref = | taxon = Labeobarbus aeneus | authority = (Burchell, 1822)

| synonyms =

• Cyprinus aeneus Burchell, 1822
• Barbus aeneus (Burchell, 1822)
• Barbus holubi Steindachner, 1894
• Barbus gilchristi Boulenger, 1911
• Barbus mentalis Gilchrist & Thompson, 1913

}

The smallmouth yellowfish (Labeobarbus aeneus) is a type of ray-finned fish. It belongs to the Labeobarbus group. This fish has become an invasive species in some rivers of the Eastern Cape, South Africa. One example is the Mbhashe River.

About the Smallmouth Yellowfish

The Orange and Vaal River system is a very important river network in South Africa. It even stretches into other countries like Botswana and Namibia. The Orange River starts in Lesotho. The Vaal River begins in Mpumalanga. These rivers flow through many different landscapes. They go from green grasslands and mountains to dry karoo and even desert areas.

Because of this, the rivers have many different habitats. You can find clear mountain streams. There are also cloudy waters in the middle Orange River. The lower parts of both rivers have nutrient-rich, discolored water. Several dams have changed how the rivers flow. This means the upper parts flow naturally. But the middle and lower parts have a controlled flow. This river system is home to the smallmouth yellowfish, L. aeneus. It is a popular fish for sport fishing in South Africa.

Life and Habits of Yellowfish

The smallmouth yellowfish is a tough and flexible fish. It lives in many places across its natural home range. It can even live in smaller streams because of its size. This fish can grow to about 9 kilograms (about 20 pounds). It eats many different things. These include plants, water insects, crabs, shrimps, and small fish.

The smallmouth yellowfish grows slowly. It also produces fewer eggs compared to its body size. It only starts to have babies when it is about 30 centimeters (12 inches) long. This usually happens when it is almost seven years old.

Reproduction and Spawning

During the time they lay eggs, male fish get special bumps on their skin. These are called sensory papillae. They make the fish feel rough to the touch. Females also have these bumps, but fewer of them. Always wet your hands before touching fish. Dry hands can remove the slimy layer that protects their skin and scales.

When the water gets warmer than 19 degrees Celsius (66 degrees Fahrenheit) in Spring, small groups of fish move. They go to shallow, rocky areas to lay their eggs. They might do this many times from October to February. Having a long spawning season helps the fish. It means they can lay eggs whenever the river conditions are good. Their eggs are quite large. They also have a double "shell." This helps the fish lay eggs in fast-moving water like rapids.

Fast-moving water has lots of oxygen. It is also a good place for algae, diatoms, and water insect larvae to grow. Young fish have silver bellies and olive-green backs. They also have black spots. They gather in small groups in good habitats.

Where Yellowfish Live

The smallmouth yellowfish is found in the Orange-Vaal river system. It has also been moved to other river systems. These include the Gouritz, Great Fish, and Kei rivers. You can also find them in the Limpopo River and Kyle Dam in Zimbabwe.

Yellowfish Habitat

This fish likes clear, flowing waters in big rivers. It prefers areas with sandy or rocky bottoms. It also does well in large dams.

What Yellowfish Eat

Larger smallmouth yellowfish eat many different things. What they eat depends on what food is available. They eat insects that live on the river bottom. This includes small clams. They also eat plants, algae, and tiny bits of dead material.

Yellowfish Status

The smallmouth yellowfish is listed as "Not Threatened." This means it is still common. It lives across the Orange-Vaal River system. There are many of them in most suitable places. However, some fish have recently died in the middle Vaal River. This is a worry. These events could harm the popular fishing spots.

Challenges for Yellowfish

Water pollution is a big problem for yellowfish. This pollution comes from city sewage plants, farms, and mines. While most of these pollutants are not directly harmful, they cause other issues. They make algae grow too much. This uses up the oxygen in the water. When oxygen levels drop too low, fish can die.

Also, bacteria that break down waste create harmful byproducts. These include ammonia and nitrites. High levels of these chemicals are very toxic to fish. Even small amounts can damage their gills.

Taking too much water from rivers in dry winter months is another threat. This can dry up parts of the river. Fish and their food sources die. Dams like the Vaal and Gariep dams also block fish from moving freely. They also change the natural flow of the river. This affects the food sources for much of the year.

Illegal fishing with nets happens in both river systems. This often occurs near informal settlements. Some landowners also do this to make extra money. Police are working to stop these illegal activities.

Several non-native fish species are now common in the Orange and Vaal rivers. The largemouth bass, which eats other fish, thrives in some dams. Carp are also common. They compete with smallmouth yellowfish for food. They also eat yellowfish eggs during spawning. The recent increase of grass carp is a serious concern. These fish grow very large and compete for food.

Fishing is a popular hobby in South Africa. Many people also fish to feed their families. Smallmouth yellowfish are caught by both groups. It is important to teach them about protecting these fish. Rules for catching yellowfish are different in each province. This makes it hard to enforce laws and inform anglers. Walking through areas where fish lay eggs can also harm them. This is especially true for fly anglers. Most provinces have laws against disturbing spawning fish.

Protecting and Using Yellowfish

Conservancies are protected areas on land. They are managed by conservation groups. If a conservancy includes a river, it helps protect the river. For these areas to work, landowners must know about river and fish issues. They need guidance on how to help.

The Orange-Vaal River Yellowfish Conservation and Management Association (OVRYCMA) helps protect yellowfish. It has 700 members who care about yellowfish. The group started in 1996 on the Vaal River. Their goals are simple:

• Create a managed conservation area.
• Release captured yellowfish back into the water.
• Educate people and help them learn more.

There are many national and provincial laws to stop illegal activities. These include pollution, illegal netting, and disturbing spawning fish. Laws also help manage smallmouth yellowfish and their homes. They set rules for fish size, how many fish can be caught, and when and where fish can be caught. A big problem is that there are not enough people to manage rivers and fish effectively.

The national River Health Programme (RHP) checks the health of fish in South Africa. Some provinces have successful RHP programs. Yellowfish are often used to show how healthy the Orange and Vaal rivers are. Many healthy smallmouth and largemouth yellowfish mean the rivers are healthy.

Research is very important. It helps managers understand fish and their environment. This helps them make good decisions. These decisions are about water flow, pollution rules, and fishing management.

Several big research projects are happening on yellowfish. These include studies on how fish move (Telemetry Project). They also look at conservation, genetics, and the economic value of the fish.

Smallmouth yellowfish are highly valued sport fish. Their closeness to the Gauteng area makes them key to the fly fishing industry in South Africa. Fishing tourism on the Vaal River is worth a lot of money each year. This includes money spent on fishing gear, travel, and food. All types of fishing have targeted this species. Organized fishing groups support efforts to protect yellowfish. Competitive fishing for these species has stopped.

People who fish for food often catch smallmouth yellowfish easily. They use natural baits like worms, crabs, and small fish. Sadly, they often catch fish when they are spawning. It is important to teach these anglers to catch other fish instead. These include the more common alien carp and the sharp-tooth catfish (barbel).

Some fishers use nets to catch carp, catfish, and moggel (Labeo umbratus). They have done this for many years in certain dams. Now, only trawl/seine nets can be used. If these nets cannot be used, a temporary permit might be given. This allows gill nets in specific areas where carp, moggel, and catfish are common.

The Free State Department of Tourism, Environmental and Economic Affairs provides smallmouth yellowfish. These fish are used to stock farm dams. This is a better choice than using non-native fish. The Gariep Dam State Fish Hatchery uses local anglers to catch smallmouth yellowfish. These fish are then kept in dams at the hatchery. They are later given to landowners to stock their dams. This method is better than breeding yellowfish. Breeding can create unwanted mixed-breed fish. It can also create fish with genes not ideal for natural systems. This plan comes from ideas developed at past Yellowfish Working Group (YWG) meetings. They stress that providing yellowfish should not be left to private companies. This is because there is no control over them. Also, yellowfish should not be moved into or within any province without a permit.