Characidae

Many fish live in warm rivers.

They live in South and Central America. These fish live in big rivers like the Amazon.

Some of these fish are very small. They are often called tetras. Scientists study how these fish are related. They move some fish into new groups. This helps us learn more about them. These fish are very interesting to see.

Characids are a family of freshwater fish. They live in warm places. Most live in Central and South America. You can find them in big rivers. The Amazon and Orinoco rivers are home to them.

These fish come in many sizes. Many of them are very small. People often call them tetras. Scientists use names to group these fish. They used to put many fish in this group. This included piranhas and fish from Africa. Now, the group is much smaller. It only has five subfamilies. A subfamily is a group of closely related fish.

Scientists study how fish are related. This is called taxonomy. They change the groups as they learn more. In 2024, they moved some fish out. They moved the families Acestrorhamphidae and Stevardiidae. These families have many colorful aquarium tetras. Moving them helps us see how fish evolved. Evolution is the way living things change over a long time. This helps us understand the history of life.

Characids are a large family of freshwater fish. They live in warm, tropical, and subtropical waters. Most of these fish live in Central and South America. You can find them in famous waterways like the Amazon and Orinoco Rivers.

These fish come in many different lengths. Many of them are quite small in size. People often call these fish "tetras" in their everyday names. Scientists use the name "characids" to describe this group of living things. This name shows they belong together in one big family.

Scientists use a system called taxonomy to group living things. This way of working helps us see how fish are related. In the past, the Characidae family was much bigger. It once included piranhas and fish from Africa called alestids. Over time, scientists changed these groups through many revisions. They moved many fish into their own separate families. For example, pencilfishes were moved into the Lebiasinidae family.

This helps scientists keep the groups more accurate.

Learning about these fish takes a long time. Many groups have changed since scientists first described them. The genus Charax and the genus Tetragonopterus were some of the first. These fish helped give the whole order its name. In 2010, the family was mostly just American tetras. But even that definition was not quite right. It did not show how much the fish had changed over time.

Scientists are always finding new ways to group them.

Today, the Characidae family is much more specific. It now contains only five subfamilies. These include Aphyocharacinae, Cheirodontinae, Exodontinae, Tetragonopterinae, and Characinae. In 2024, two more families were split out. These new families are called Acestrorhamphidae and Stevardiidae. They contain many of the colorful tetras seen in aquariums.

This recent change helps show the true diversity of the fish.

If you have ever seen a colorful fish in a tank, it might be a characid. Many people keep ornamental tetras as pets in their homes. These fish are part of a huge web of life in the rivers. Understanding them helps us learn about the history of the Earth. By studying how they change, we learn about evolution. Evolution is how living things change over a very long time.

Every new discovery tells us more about our world.

Characidae is a large family of freshwater fish. These fish live in subtropical and tropical environments. Most members of this family live in Central and South America. You can find them in massive waterways like the Amazon and Orinoco Rivers.

Many people know these fish by common names like "characins" or "tetras." While they vary in length, many species are quite small. Scientists use the term "characids" to describe this group. This name reflects that they are a monophyletic group. This means they all share a single common ancestor at the family rank.

Taxonomy is the scientific study of how we classify living things. Scientists use taxonomy to organize fish into groups based on their relationships. The classification of Characidae has changed many times. In the past, the family had a much broader definition. It once included many different groups of fish. For example, it used to include piranhas and dorados. It even included the alestids, which are fish from Africa.

Over time, researchers performed multiple taxonomic revisions. These revisions moved many fish into their own distinct families.

As scientists learned more, they realized the old groups were not accurate. Many former members were moved to separate families. The pencilfishes of the genus Nannostomus moved to the Lebiasinidae family. Predatory species like Hoplias moved to the Erythrinidae family. Even the sabre-toothed Hydrolycus moved to the Cynodontidae family. After 1994, many other groups were also moved out. This included families like Anostomidae, Chilodidae, and Serrasalmidae. These changes help scientists show the true evolutionary history of the fish.

Today, the Characidae family is much more specific than it used to be. By the 2010s, the definition was mostly restricted to American "tetra" type characins. However, even that definition did not show all the evolutionary diversity. In 2024, scientists made more changes to the group. They split out two new families called Acestrorhamphidae and Stevardiidae. These two families contain many of the famous ornamental tetras used in aquariums. The family Spintherobolidae was also split out.

This leaves Characidae with just five subfamilies.

The current Characidae family is organized into five distinct subfamilies. The first is Aphyocharacinae, which includes genera like Aphyocharax and Amazonichthys. The second is Cheirodontinae, which contains many genera like Cheirodon and Pseudocheirodon. The third subfamily is Exodontinae, which includes the genus Exodon. The fourth is Tetragonopterinae, which contains the genus Tetragonopterus. Finally, there is the subfamily Characinae. This subfamily includes the genus Charax and several others.

Each subfamily represents a different branch of the family tree.

History shows us which fish helped scientists name this group. The genera Charax and Tetragonopterus were among the first characiforms described to science. Because they were so early in the study of these fish, they helped give the entire order its name. The name "Characinae" is a very narrow term used in recent studies. It only covers twelve genera and 79 species. These species are very closely related to the genus Charax.

Understanding these early discoveries helps us see how our scientific knowledge grows.

Characids are important to both science and the human world. Many people keep ornamental tetras as pets in home aquariums. These fish are part of a complex web of life in tropical rivers. Studying them helps us understand how species change over time through evolution. By looking at how families like Characidae are split and reorganized, we see how biology works. Each revision provides a clearer picture of the natural world.

This constant discovery helps us map the history of life on Earth.