Grass carp

The grass carp is a big fish.

It lives in rivers and lakes. These fish love to eat plants. They can eat a lot of food every day. They eat up to three times their weight!

These fish grow very fast. They can get quite long. They have dark green sides. Their bellies are white.

People use them to help clean water. They eat the weeds in lakes. This keeps the plants from growing too much.

They are very strong swimmers. You can find them in many lands. They are amazing fish to see.

The grass carp is a large fish. It lives in fresh water like rivers and lakes.

These fish are herbivores. This means they mostly eat plants. They can eat up to three times their own weight every day! They like to eat underwater weeds and other plants. Because they eat so much, people use them to control weeds in lakes.

Grass carp have long, chubby bodies. They look like torpedoes. Their sides are dark olive color. Their bellies are white. They grow very fast. A young fish can grow a lot in just one spring. They can grow to be 1.5 meters long.

These fish come from the Pacific Far East. They live in places like Vietnam and China. People in China have farmed them for a long time. They are one of the "Four Great Domestic Fish" in China.

In the wild, they spawn in fast rivers. This means they lay eggs in moving water. The eggs need to drift in the current. If they sink to the bottom, they might die.

The grass carp is a huge freshwater fish. It belongs to a group called Cyprinidae. This fish is a herbivore, which means it mostly eats plants.

People use them to help clean up lakes. They eat many types of underwater weeds. This makes them very useful for weed control. They are even one of the most farmed fish in the world. They produce over five million tonnes every year.

These fish have a very specific way of growing and living. They have long, chubby bodies shaped like torpedoes. Their sides are dark olive, but their bellies are white.

They grow very fast in the water. A young fish can grow a lot between spring and fall. Most grow to about 1 meter long. Some can even reach 1.5 meters. They have special teeth in their throat to help them eat. These teeth are arranged in a pattern called "2, 4-4, 2."

In the wild, grass carp have a tricky way of making babies. They go to fast-moving rivers to spawn. This is when they lay their eggs. The eggs are slightly heavier than the water.

Because they are heavy, they need fast water to keep them moving. The moving water keeps the eggs floating in the middle. If the eggs sink to the bottom, they might die. This is why they need long, rushing rivers to survive.

We can learn about these fish from very old fossils. Scientists found fossil teeth from extinct relatives in China. These relatives lived during the Early Miocene period.

The modern grass carp has fossils from the Early Pliocene. People in China have farmed these fish for centuries. They are one of the "Four Great Domestic Fish." In the United States, they were first brought from Taiwan and Malaysia in 1963. They were first released in Arkansas in 1966.

You might see grass carp in many different places today. They were moved to the United States to help manage plants. They are now found in 45 of the 50 states.

Some people use sterile fish called triploid grass carp. These fish cannot make babies, so they stay safe in local lakes. People also enjoy fishing for them because they are strong fighters. A world record fish was caught in Bulgaria in 2009. It weighed 51.1 kilograms.

The grass carp, known scientifically as *Ctenopharyngodon idella*, is a large herbivorous fish. This means it primarily eats plants rather than other animals. It belongs to the family Cyprinidae. This species is native to the Pacific Far East. Its natural range extends from northern Vietnam to the Amur River on the Sino-Russian border. Today, it is one of the most important fish in the world for aquaculture.

Global production of this species is massive. It exceeds five million tonnes every single year.

Physically, the grass carp has a very distinct appearance. It possesses an elongated, chubby, torpedo-shaped body. The color of the body is typically a dark olive. This color often shades into a brownish-yellow along the sides. The belly of the fish is white. Its scales are large and have slight outlines. The fish lacks barbels, which are the whisker-like structures seen on other carp. Instead, it has a terminal mouth with firm, non-fleshy lips.

The lateral line, a sensory organ along the side, contains 40 to 42 scales.

To eat its heavy diet of vegetation, the grass carp uses specialized tools. It has broad, ridged pharyngeal teeth located in its throat. These teeth follow a specific arrangement called a "2, 4-4, 2" formula. This structure helps the fish process plant matter effectively. Adult grass carp are incredibly hungry eaters. They can consume up to three times their own body weight in food every day. They mostly eat aquatic plants and submerged terrestrial vegetation. However, they may also eat insects, invertebrates, or detritus.

These fish are famous for their rapid growth rates. If you stock young fish in the spring, they grow significantly by the fall. A typical adult reaches about 1 meter in length. However, they can reach a maximum length of 1.5 meters. They are quite strong and can weigh a great deal. In 2009, a world record grass carp was caught in Bulgaria. That fish weighed 51.1 kilograms.

Most grass carp live between 5 and 9 years. Some have been known to live 11 years. In Silver Lake, Washington, a population has even passed the 15-year mark.

The reproductive process of the grass carp is very specific. In the wild, they spawn in fast-moving rivers. This is necessary because their eggs are slightly heavier than the water. The turbulence of the fast river keeps the eggs in suspension. This prevents the eggs from sinking to the bottom. If the eggs sink, they are thought to die. Because of this, the species requires long, rushing rivers for its young to survive.

This explains why they only establish self-reproducing populations in a few specific rivers.

Humans have a long history with this species. In China, grass carp have been cultivated for centuries. It is recognized as one of the "Four Great Domestic Fish." Because its meat is tender and has few bones, it is a popular food. In the United States, the fish was first imported in 1963 from Taiwan and Malaysia. An accidental escape in 1966 from an experimental station in Arkansas led to widespread presence. By the 1970s, the fish was in 40 states. It is now reported in 45 of the 50 United States.

Today, grass carp serve a major role in environmental management. They were introduced to many countries for aquatic weed control. For example, New Zealand used them to manage plant growth. In the Netherlands, they were introduced in 1973 for the same purpose. To prevent these fish from spreading uncontrollably, scientists use triploid grass carp. Triploid fish are sterile, meaning they cannot reproduce. This allows managers to use their eating habits to clean up lakes without worrying about new populations forming.

We can also learn about the history of this genus through fossils. The modern grass carp is the only living member of *Ctenopharyngodon*. However, two extinct species were found in China. These were identified from fossil teeth in the Xiacaowan and Xiejia formations. The earliest fossils of the modern species appear in the Gaozhuang Formation. Other related extinct genera, such as *Eoctenopharyngodon*, lived during the Oligocene period. This shows that this lineage of fish has a very deep history in the Earth's record.