Carassius

Some fish are very special. One kind is the goldfish. They are part of a big group. Most in this group are called crucian carps. These fish live in many lands. They come from places in Europe and Asia. They may come from the west. Some look white. Some are called Prussian carp. There are many kinds of these fish. They are fun to see in the water.

There is a big group of fish called Carassius. Most of these fish are crucian carps. The most famous one is the goldfish. These fish live in Europe and Asia. This is called a Eurasian distribution. Scientists think they come from the west. They are part of a family called Cyprinidae. This is a family of ray-finned fish. Scientists use molecular phylogenetics to study them. This is a way to study DNA. This helps them see how fish are related. They found a group called Carassiodes. This group sits inside the Carassius group. There are many different species in this group. One is the Japanese white crucian carp. Another is the Prussian carp. There is also a fish called Ginbuna. A new kind called Carassius praecipuus was found in 2017. Each fish is part of this big family tree.

The genus Carassius is a group of fish. Most of these fish are called crucian carps. You likely know the most famous one. It is the goldfish. These fish are part of a larger family called Cyprinidae. This family is made of ray-finned fish. These fish are very important to study. They show us how different species are related.

Scientists study how these fish are related. They use a method called molecular phylogenetics. This is a way to study DNA to find connections. This study helps map out a family tree. Researchers found that the genus Carassiodes is nested inside Carassius. This means Carassiodes is part of the larger group. This group is also a sister to the Cyprinus genus. The Cyprinus genus includes the common carp.

People have named these fish for a long time. Carl Linnaeus named the goldfish in 1758. He also named the crucian carp that same year. Other scientists added more names later on. Temminck and Schlegel named several species in 1846. These included the buergeri and the cuvieri. Bloch named the Prussian carp in 1782. History helps us track these discoveries.

There are many different species in this group. The goldfish is known as Carassius auratus. The crucian carp is Carassius carassius. There is also the Japanese white crucian carp. Its name is Carassius cuvieri. Another is the Prussian carp, or Carassius gibelio. We also find the Ginbuna, or Carassius langsdorfii. A new species, Carassius praecipuus, was found in 2017. These fish have a Eurasian distribution.

These fish live in Europe and Asia. This area is called a Eurasian distribution. They likely started in the west. This is different from typical carps. Most carps come from other places. You might see these fish in a pet store. They are a big part of the natural world. Learning about them helps us understand all fish.

The genus *Carassius* is a group of fish within the ray-finned family Cyprinidae. Most fish in this genus are known as crucian carps. However, that name often refers specifically to one species, *Carassius carassius*. The most famous member of this group is the goldfish, known scientifically as *Carassius auratus*. These fish are significant to biologists studying evolution and classification. They help scientists understand how different types of fish branched off from common ancestors.

Scientists use a method called molecular phylogenetics to study these fish. Molecular phylogenetics is the study of DNA to find evolutionary relationships. This process helps researchers build a biological family tree. Current research suggests the genus *Carassius* might not be monophyletic. A monophyletic group is a group that includes a single common ancestor and all its descendants. Instead, studies show that the genus *Carassiodes* is nested within *Carassius*. This means *Carassiodes* is actually part of the *Carassius* group.

This evolutionary structure shows a close relationship between different genera. The *Carassius* group is considered a sister to the genus *Cyprinus*. The *Cyprinus* genus includes the common carp. Being a sister group means they share a common ancestor. This relationship helps scientists map out the history of the Cyprinidae family. It shows how these different lineages moved and changed over time.

There are several distinct species within the *Carassius* genus. One species is *Carassius auratus*, which is the goldfish. Another is *Carassius carassius*, the crucian carp. Scientists also recognize *Carassius buergeri* and *Carassius cuvieri*. The latter is known as the Japanese white crucian carp. There is also the Prussian carp, or *Carassius gibelio*. Another member is the Ginbuna, named *Carassius langsdorfii*. Finally, a newer species called *Carassius praecipuus* was identified.

The history of naming these fish spans many centuries. Carl Linnaeus named both the goldfish and the crucian carp in 1758. Later, Bloch named the Prussian carp in 1782. In 1846, scientists Temminck and Schlegel named several species. These included *Carassius buergeri* and *Carassius cuvieri*. More recently, the species *Carassius praecipuus* was named by Kottelat in 2017.

These fish have a Eurasian distribution. This means they are found across Europe and Asia. Evidence suggests they may have originated further to the west than typical carps. The typical carps belong to the *Cyprinus* genus. This geographical detail helps researchers understand how the fish spread across the continent. It also helps them track how different environments shaped the species.

Understanding *Carassius* connects us to broader biological concepts. It allows us to study how species are classified and organized. By looking at the DNA of these fish, we learn about the history of life. We see how small changes in genes can lead to new species. This genus serves as a vital example of how scientists use modern tools to solve old mysteries.