Characiformes

Many fish live in rivers and lakes.

Some are very big. Some are quite small.

Many have bright colors. You might see them in a tank at home.

These fish have scales on their bodies. Most of them have teeth in their mouths. This helps them eat.

Some fish, like the piranha, are well known.

Most of these fish live in the Americas. They live in South and Central America. Some also live in Africa. They like to swim in groups.

Some of these fish are very large. They can be good to catch for food. The smallest ones are tiny. They are very different from the big ones.

It is fun to learn about them. They are a big part of the water world.

Characiformes are a large group of fish. They include many different kinds. You may know the piranha. You might also know tetras.

There are over 2,000 species in this group. Most live in South and Central America. Some live in Africa too.

These fish have special parts. They have a Weberian apparatus. This is a set of bony parts. They connect the inner ear to the swim bladder. This helps the fish sense things. Most have scales on their bodies. Many have teeth to help them eat.

Some fish in this group are very big. The goliath tigerfish is one. The golden dourado is another. The smallest is the pygmy blue characin. It is very tiny.

Many tetras are small. They swim in groups. People like them in home tanks. They have bright colors. They are also very hardy. This means they stay healthy easily.

Characiformes is a large group of ray-finned fish. This group includes many famous animals like the piranha and the tetra.

There are more than 2,000 different species in this order. Most of these fish live in the Neotropics. This means they are found in rivers and lakes in South and Central America.

Some species also live in Africa. At least 209 species of characins are found there. They are very important to many different water habitats around the world.

These fish have a special way they work. They have a Weberian apparatus inside their bodies. This is a series of bony parts. These parts connect the swim bladder to the inner ear.

Most characins also have teeth in their mouths. This is because many of them are carnivorous, or meat-eaters. Their bodies are almost always covered in well-defined scales. Some might even have a small, fleshy adipose fin. This fin sits between the dorsal fin and the tail.

Scientists have studied these fish for a long time. In the past, all characins were put into one single family called Characidae. Now, researchers have separated them into 18 different families.

A study from 2011 helped confirm how these families are related. The Characiformes are part of a larger group called the Otophysi. This group also includes other fish like catfish and carp. It is amazing to see how much our understanding of them grows.

There are many different sizes in this group. The goliath tigerfish is one of the largest.

The golden dourado and the wolffish are also very large. On the other side, the pygmy blue characin is tiny. It is about 10 millimeters long. Most characins are actually small fish that swim in groups. These are often called forage fish. Many tetras are popular in home aquaria. People like them because they have bright colors and are hardy.

These fish tell us a story about our planet. They likely started in the West Gondwana supercontinent. This land later split into Africa and South America. This split explains why they are found in both places today. Fossil teeth show they lived in places like Hungary and Morocco. Some fossils were even found in North America. This suggests the world was much warmer during the Cretaceous period. Warm water allowed them to live much further north than they do now.

Characiformes is a massive order of ray-finned fish. It includes the characins and many of their close relatives. This group is incredibly diverse, containing over 2,000 different species. You might recognize some of them, like the famous piranha or various types of tetras.

These fish play vital roles in the ecosystems where they live. They are found in many different freshwater environments around the world.

Most characins live in the Neotropics. This region includes the rivers and lakes of South and Central America. However, they are not only found in the Americas. At least 209 species live in Africa. These African species include groups like the distichodontids, citharinids, alestids, and hepsetids.

The vast majority of characins, however, are native to the Americas.

Characins have unique physical features that help them survive. One special feature is the Weberian apparatus. This is a series of bony parts inside the body. These bones connect the swim bladder to the inner ear.

This connection likely helps them sense sounds. Most characins also have teeth because they are often carnivorous. Their bodies are usually covered in well-defined scales. Some species even have a small, fleshy adipose fin. This fin is located between the dorsal fin and the tail.

Scientists categorize these fish into many different groups. The Characiformes belong to a larger group called the Otophysi. The Otophysi also include the orders Cypriniformes, Siluriformes, and Gymnotiformes. Within the Characiformes, there are 18 recognized families and about 270 genera.

Originally, scientists placed all characins into just one family called Characidae. Modern research has since separated them into many distinct families. A 2011 study helped confirm that the Characidae family is monophyletic, meaning they share a common ancestor.

The sizes of characins vary wildly. Some species are very large and are important for food or game. The goliath tigerfish, known as Hydrocynus goliath, is one of the largest.

Other large examples include the golden dourado and the wolffish. In contrast, many characins are very small. The smallest is the Bolivian pygmy blue characin, which is only about 10 millimeters long. Many small species are called forage fish because they swim in large groups called shoals. Many tetras are popular in home aquaria because of their bright colors and hardiness.

The history of these fish is tied to the movement of continents. Characiforms likely originated on the supercontinent of West Gondwana. This landmass later split into Africa and South America. This geological split explains why they are found on both continents today. During the Cretaceous period, the Atlantic Ocean was forming between these lands. Fossil evidence shows that characins once lived much further north than they do today. This includes fossils found in places like Hungary, Morocco, and North America. Scientists believe the warmer climate of the Late Cretaceous allowed them to live in these northern regions.

Understanding Characiformes helps us learn about evolution and Earth's history. Their distribution reflects how landmasses have shifted over millions of years. By studying their fossils and their DNA, researchers can trace how life changes. The way they interact with other fish also shows how ecosystems work. From tiny tetras to massive tigerfish, they are a key part of the world's freshwater life.