Wels catfish

The wels catfish is a very big fish.

It lives in deep rivers and lakes. It can grow very long and heavy.

This fish has a slimy skin. It uses smell to find food. Some fish are even white instead of dark.

They can live for many years. One fish lived for 70 years! This fish is a very strong swimmer.

The wels catfish is a very large fish.

It lives in parts of Europe and Asia. These fish like deep, slow rivers and warm lakes. They often hide in holes or near sunken trees.

This fish has a long body. It can swim backwards just like an eel. Its skin feels very slimy. The color of its skin changes with its home. In clear water, the fish looks black. In muddy water, it may look green-brown. Some fish are born without color. These are called albino fish.

To find food, the wels catfish uses smell and hearing. It is most active at night. It has a special part in its eyes to help it see in the dark. This is called a tapetum lucidum. It eats many things like worms, insects, and other fish. Some large fish even lunge out of the water to catch birds!

These fish can live a long time. One fish in Sweden lived for 70 years.

Females can lay up to 30,000 eggs. The male fish stays to guard the nest.

The wels catfish is one of the largest freshwater fish in Europe and Western Asia. It is a massive creature that can grow to be very long. Only two other fish, the sturgeon species, are larger in these regions.

These fish live in large, warm lakes and deep, slow rivers. They like to hide in sheltered spots like holes in the riverbed or near sunken trees. Because they are so big, they are often caught by people for sport fishing.

This fish has a very special way of finding food. It mostly hunts at night using its sense of smell and hearing. It has a special part in its eyes called a tapetum lucidum. This part helps the fish see better in the dark.

When it finds prey, the catfish uses its sharp pectoral fins to create a swirling current. This current confuses the victim. Then, the catfish sucks the prey into its large mouth and swallows it whole. They eat many things, including worms, insects, and even birds like pigeons.

Scientists have studied these fish for a very long time. Fossil remains show they lived in Ukraine about 5.3 million years ago. During the Pliocene period, they grew to fill more areas. They were more adaptable than other catfish, like the Soldatov's catfish. The wels catfish could handle cooling and drying weather much better. This helped them take over more space in eastern Europe. They are very long-lived animals that can survive for many decades.

There are many amazing records for this species. A fish in Sweden was recently found to be 70 years old. In Germany, a record fish was 2.78 meters long and weighed 137 kilograms. In Poland, a specimen reached 2.61 meters and 109 kilograms. Another large fish was caught in the Po River in Italy in 2010. It weighed 110 kilograms.

Even some fish can be born without color, which are called albino specimens.

Because they are top predators, these fish change the places they live. If they are moved to new rivers, they can eat many other local fish. In the Ebro basin, some fish species have disappeared because of them.

Some people even keep them in ponds for food. However, people usually only eat them when they are smaller than 15 kilograms. Larger fish can be very fatty and may have toxins in them. Most people prefer to catch them for the excitement of the hunt.

The wels catfish, known scientifically as *Silurus glanis*, is a massive freshwater fish. It is found throughout central, southern, and eastern Europe. Its range also includes the basins of the Baltic, Black, and Caspian Seas. It has been introduced to parts of Western Europe, the Mediterranean, and Asia as a prized sport fish. Today, its range stretches from the United Kingdom in the west to western China in the east.

This species is one of the largest freshwater fish in Europe and Western Asia. Only the Atlantic and beluga sturgeon are larger in these regions.

This predator has a very specialized way of hunting. It relies heavily on hearing and smell to find prey. This is possible because of its sensitive Weberian apparatus and chemoreceptors. These organs help it detect movement and chemical signals in the water. The wels catfish is also nocturnal, meaning it is most active at night. Its eyes have a tapetum lucidum, which is a reflective layer that helps it see in low light. When it finds a victim, it uses its sharp pectoral fins to create an eddy, or a swirling current. This movement disorients the prey. The catfish then sucks the victim into its large mouth and swallows it whole.

The physical appearance of the wels catfish varies based on its environment. Its skin is very slimy and its color changes depending on the water. In clear water, the fish often appears black. In muddy water, specimens tend to be green-brown. The underside is always a pale yellow or white. Occasionally, albino specimens are caught, which lack normal skin pigment.

The fish has an elongated body shape. This allows it to swim backwards, much like an eel. Its mouth contains many small teeth and several barbels. It has two long barbels on the upper jaw and four shorter ones on the lower jaw.

Fossil evidence shows that the wels catfish has a long history. The earliest identifiable fossils are from the late Miocene, about 5.3 million years ago, in Ukraine. Some less well-preserved remains might be 6 to 7 million years old. During that time, the Soldatov's catfish was the dominant species in eastern Europe. That species was better adapted to the warm climate. However, the wels catfish was more adaptable to cooling and drying trends. During the Pliocene, the wels catfish expanded its range. It eventually replaced the Soldatov's catfish in the region.

These fish are capable of incredible growth and longevity. Most adults are about 1.5 meters long and weigh around 20 kilograms. However, they can grow much larger under excellent conditions. A record fish in Germany was 2.78 meters long and weighed 137 kilograms. In Poland, a specimen reached 2.61 meters and 109 kilograms. The heaviest authenticated specimen was caught in Italy's Po River in 2010, weighing 110 kilograms. They are also very long-lived. A study in Sweden recently identified a specimen that was 70 years old.

The diet of the wels catfish is highly opportunistic. It usually eats worms, insects, crustaceans, and other fish. Larger fish may eat eels, frogs, snakes, rats, and even aquatic birds.

In France, researchers documented catfish lunging out of the water to catch pigeons. This behavior was observed in an introduced environment. In their native range, they are mainly nocturnal bottom-feeders. However, they can adapt to new food sources. They have even been seen eating dead Asian clams at the water's surface during the day.

Because they are top predators, they can impact local ecosystems. When introduced to new areas, they can cause steep declines in other fish populations. In the Ebro basin, they have caused the disappearance of certain Iberian barbels. They also change the environment by increasing the growth of aquatic vegetation like algae. In Sweden, the species is considered near threatened due to declining numbers. Some populations are also genetically isolated. While they are not globally endangered, their status varies by region. People often catch them for sport, but they are only recommended for food when they are under 15 kilograms.