Acanthurus lineatus – Lined Surgeonfish

Acanthurus lineatus – Lined Surgeonfish

Acanthurus lineatus was first described by Carl Linnaeus in 1758. This fish belongs to the family Acanthuridae, which is also known as surgeonfish and unicornfish. The family Acanthuridae consists of six genera, including the genus Acanthurus, which contains about 40 species.

The genus name Acanthurus is derived from the Greek “akantha” (thorn) and “oura” (tail), referring to the sharp thorn on either side of the tail. The species name lineatus means “striped” in Latin, referring to the yellow and blue stripes on the fish’s body.

Synonyms:

• Chaetodon lineatus
• Ctenodon lineatus
• Harpurus lineatus
• Hepatus lineatus
• Rhombotides lineatus
• Teuthis lineatus
• Acanthurus vittatus

Description

General description:
Acanthurus lineatus has a deep and laterally flattened body. The head and flanks are covered with alternating black-bordered blue and yellow stripes, while the underside of the body is a pale lavender to bluish-white color. The fins are also colorful: the dorsal fin is finely striped in light blue and yellow, the anal fin is gray with a yellow basal band and a light blue border, and the caudal fin is blackish with a large gray crescent in the center. This fish can reach a maximum length of 38 centimeters.

Differences between males and females:
There are no obvious physical differences between males and females of this species. Behaviorally, however, males are territorial and will defend a territory with a harem of females.

Behavior and temperament:
Acanthurus lineatus is territorial and can be aggressive, especially towards conspecifics and other fish that invade its territory. Adults may swim in schools, especially during spawning, while juveniles are usually solitary. They are primarily herbivorous and graze on algae during the day.

Life expectancy:
In the wild, these fish can live up to 46 years.

The Scalpels

Acanthurus lineatus, also known as the Lined Surgeonfish, has a distinctive feature that sets it apart from many other fish species: the sharp, scalpel-like spines on both sides of its tail. These spines, also called “scalpels,” are an important defense mechanism for the fish.

Features of the Scalpels

1. Location and Structure:
   The scalpels are located at the base of the caudal fin, on the caudal peduncle. They are lance-shaped and can be extended when the fish feels threatened.
2. Function:
   The scalpels serve as defensive weapons against predators and other fish. When the fish feels threatened, it can use these sharp spines to ward off attackers. This mechanism is particularly effective because of the sharp edge and the ability to inflict deep cuts.
3. Poisoning:
   The spines are covered with a poisonous mucus layer, which further increases the effectiveness of the defense. A sting from these spines can be very painful and cause infections in attackers, including humans.
4. Behavior:
   During territorial conflicts or when the fish feels threatened, it may extend its spines and use them in aggressive interactions. This behavior is often observed when defending their territory from intruders.
5. Warning:
   Although the spines are not always visible, the fish can change their body posture and color patterns to warn potential threats of their presence. This can be a visual warning to other fish to stay away.

The sharp scalpels on the tail of Acanthurus lineatus are a crucial part of their defense mechanism. These spines provide protection from predators and help maintain territorial boundaries. Aquarists must be careful when handling these fish to avoid injury.

Biotope

The Lined Surgeonfish is found in the Indo-Pacific region, including the coasts of East Africa, the Mascarene Islands, Hawaii, the Marquesas Islands, southern Japan, the Great Barrier Reef, and New Caledonia. It primarily inhabits coral reefs and lagoons, often in shallow coastal waters and near wave action zones. Its natural habitats consist of coral and rocky environments with abundant algae.

Diet

In the wild:
Acanthurus lineatus feeds mainly on algae, but may also eat small crustaceans.

In the aquarium:
In the aquarium they should be fed a diet rich in plant material such as macroalgae (e.g. seaweed/nori) and microalgae (e.g. spirulina). They can also eat small crustaceans such as krill, mysis and artemia.

Reefsafe:
Yes, this species is reefsafe and does not eat coral, polyps or shrimp.

The Aquarium

Aquarium size:
An aquarium should be at least 1000 liters to hold one specimen. To minimize territorial conflicts, an even larger aquarium is needed for multiple specimens.

Setup:
The aquarium should be decorated with lots of coral and rocks to provide hiding places and to grow algae. Use a sand or fine gravel substrate.

Water parameters:
Ideal water parameters are a temperature of 24-30°C, a pH of 8.0-8.5, and a specific gravity of 1.020-1.025.

Introduction:
Only introduce this species into a well-matured aquarium with sufficient algae.

Compatibility:
This species does well with other peaceful reef fish such as clownfish, gobies, and wrasses, but avoid keeping them with other aggressive or territorial fish.

Breeding Acanthurus lineatus

There are no specific data available on breeding Acanthurus lineatus in an aquarium. In the wild, they form spawning groups and lay eggs in open water.

The spawn

During spawning, the colors of the fish can become more intense. Spawning usually takes place in the morning and the eggs are laid in open water. The exact number of eggs and their size and color are not documented.

Raising the fry

No specific data is available on hatching. In the wild, the young tend to remain in shallow water until they reach adulthood.

Particularities

A special feature of the Acanthurus lineatus is their territorial behavior and the aggression they show towards intruders, both of their own species and of other species. They also have a sharp, poisonous thorn on each side of their tail, which they use for defense

Conclusion

Acanthurus lineatus is a beautiful but challenging fish to keep in an aquarium. They require a large tank with plenty of hiding places and a diet rich in plant material. Their territorial and aggressive behavior makes them unsuitable for beginners, but with the right care and environment, they can be an impressive addition to a well-maintained reef tank.

Video

Author

John de Lange

Copyright images

Russell Gilbert
Hristo Hristov
Rickard Zerpe – CC BY 2.0
zsispeo – CC BY-NC-SA 2.0
Paul Asman en Jill Lenoble – CC BY 2.0