Acanthuridae

Many bright fish live in warm seas.

These fish are called surgeonfish. They have sharp spines on their tails. These spines can be very pointy.

These fish use their small mouths to eat plants. They have one row of teeth to help. Some fish swim in big groups. This helps them stay safe.

Baby fish look very different from adults. They are clear and live in open water. They grow fast as they get older.

Many bright fish live in warm, tropical seas.

These fish belong to a group called Acanthuridae. People call them surgeonfish, tangs, or unicornfishes. There are about 86 types of these fish.

They have a special part on their tails. They have sharp, bony plates on the tail stem. These plates act like scalpels. They can be very sharp and may cause injury.

Most of these fish are quite small. However, some types can grow much larger. The whitemargin unicornfish is the largest. It can reach 45 centimeters in length.

Young fish look very different from adults. They go through an acronurus stage. This means they are clear and live in open water. Later, they move to the ocean bottom.

Surgeonfish have small mouths with one row of teeth. They use these teeth to graze on algae. They have special bacteria in them to help. These tiny living things help them digest the plants. Some fish swim in schools to eat. This helps them deal with small, mean fish.

These small fish guard patches of algae on reefs.

Many bright fish live in warm, tropical seas around coral reefs. These fish belong to a group called Acanthuridae. People often call them surgeonfish, tangs, or unicornfishes. There are about 86 different species living in these oceans today. These fish are very popular in aquariums because of their colors.

They are important parts of the life in the sea.

These fish have a very special way of protecting themselves. They have sharp, bony plates on the stem of their tails. This part of the tail is called the caudal peduncle. The name Acanthuridae comes from Greek words for "spine" and "tail." These plates act like scalpels and are very sharp. They can cause a serious injury if a person is not careful. This is how the family gets its common name.

Surgeonfish have a unique way of growing and eating. They start life as tiny, clear larvae called acronurus.

These young fish live in open water for a long time. Later, they settle on the ocean bottom to grow into adults. They have small mouths with one row of teeth. These teeth help them graze on algae like Caulerpa. They even have special bacteria to help them digest this food.

Scientists have studied these fish for a long time. In the early 1900s, people called this family Hepatidae. We also know about their ancestors from fossils. Some fossils come from a place in Italy called Monte Bolca. These fossils date back to the Eocene and Miocene times. This shows that different types of surgeonfish have existed for a very long time. Many different groups, called tribes, can be seen in the fossil record.

Most surgeonfish stay quite small as they grow. However, some types can become much larger than others. The whitemargin unicornfish is the largest in the whole family.

It can reach a length of 45 centimeters. Other large types include fish from the genus Naso and Prionurus. People who keep them in tanks must give them plenty of room. This is because they need space to swim and places to hide.

The Acanthuridae are a diverse family of ray-finned marine fishes. They include many well-known groups like surgeonfishes, tangs, and unicornfishes. These fishes live in tropical seas, mostly around coral reefs. There are approximately 86 different species currently living in our oceans. Because of their bright colors, many species are very popular in home aquaria.

The name of this family reveals a key physical feature. It comes from the Ancient Greek words "akantha," meaning spine, and "oura," meaning tail. This refers to the sharp, bony plates found on the caudal peduncle. The caudal peduncle is the narrow part of the body where the tail attaches. These plates are shaped like scalpels and are dangerously sharp. They can cause serious injury to anyone who handles the fish carelessly.

Surgeonfishes have specific body parts that help them survive. Their dorsal, anal, and caudal fins are quite large. These fins extend across most of the length of their bodies. They also have small mouths containing a single row of teeth. These teeth are specifically adapted for grazing on algae. While some fish feed alone, others travel in schools. This schooling behavior may help them overwhelm aggressive damselfishes. Damselfishes are small, territorial fish that guard patches of algae on reefs.

These fishes go through a very interesting life cycle. They begin life as larvae known as acronurus. An acronurus looks very different from the adult fish. These larvae are mostly transparent and live a pelagic lifestyle. This means they spend much of their time in the open ocean water. Eventually, they settle on the ocean bottom near the shore. Once they settle, they develop into juveniles and then into adults.

Digestion in surgeonfishes relies on a unique biological partnership. They are the only known hosts for bacteria in the genus Epulopiscium. These symbiotic bacteria live inside the fish and help with digestion. This process allows the surgeonfish to properly digest the algae in their diet. In the wild, they primarily graze on macroalgae. Common types include genera such as Caulerpa and Gracilaria.

We can learn about the history of these fish through fossils. Several extinct genera have been identified from the Eocene to the Miocene epochs. A large variety of fossil surgeonfish comes from the Monte Bolca lagerstatte in Italy. These fossils represent some of the earliest members of specific tribes. Scientists have identified many extinct genera, such as Acanthuroides and Metacanthurus. In the early 1900s, researchers actually referred to this family as Hepatidae.

Size varies greatly among the different species in this family. Most species remain fairly small as adults. However, certain genera like Acanthurus and Prionurus can grow larger. The genus Naso also contains many larger species. The largest member of the entire family is the whitemargin unicornfish, or Naso annulatus. This species can reach a total length of up to 45 centimeters.

Keeping these fish in aquariums requires careful planning. Many species, especially tangs, are very sensitive to diseases. Aquarists often use a technique called a refugium to help. They grow macroalgae in a separate area to absorb nitrates. This improves the water quality for the fish. Because many tangs are territorial, they may fight with other fish. Owners must ensure there is enough swimming room and many places to hide.