Lined Surgeonfish (Acanthurus lineatus)

Lined Surgeonfish at a glance

The Lined Surgeonfish (Acanthurus lineatus) is a marine surgeonfish from the coral reefs of the Indo-Pacific, and its pattern is unmistakable. Blue stripes edged in black alternate with yellow along the upper three-quarters of the body, the stripes on the head run mainly on the diagonal, and the lower quarter is a pale lavender to bluish white. The body is deep and flattened from side to side, and the tail fin is deeply crescent-shaped. It is also called the blue banded, clown, striped or zebra surgeonfish, and the pyjama tang. The World Register of Marine Species lists it as an accepted species in Acanthuridae, the family of surgeonfishes, tangs and unicornfishes.

Its natural range is enormous. FishBase records it from East Africa and the Mascarene Islands east to the Hawaiian, Marquesas and Tuamotu islands, north to southern Japan and south to the Great Barrier Reef and New Caledonia; in the Red Sea its place is taken by the closely related Acanthurus sohal. It lives in shallow water, from the surface down to about 15 m and usually just 1–3 m deep, and is common in the surge zones of exposed seaward reefs.

This is a fish for experienced marine keepers with a genuinely large aquarium. It reaches a recorded maximum of 38 cm, it is almost always on the move, and it guards its own grazing ground. It also carries a venomous spine on each side of the tail base, which matters every time your hands are in the water. If you are still planning a first saltwater aquarium, this is a species to admire now and to keep once you have the space and experience it needs.

What you receive

Each purchase supplies one live Lined Surgeonfish. The 38 cm figure is the species' recorded maximum length, not the size of the fish that arrives, so plan the aquarium for the adult from the start rather than for the fish in the bag. Moving a large tang with venomous spines into a bigger aquarium later is a difficult job, so starting with the right volume is the safer plan.

Sex is guaranteed only when the selected option explicitly states male or female. This Lined Surgeonfish listing has no sex-guaranteed option.

Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals. The photograph shows the features that identify the species: black-edged blue stripes on a yellow body, a pale belly and a deep, crescent-shaped tail fin.

In a large display it is a fish you watch rather than search for. FishBase describes it as active by day and almost continually in motion, and it spends much of that time grazing, so it covers the whole length of the aquarium many times over and rarely tucks itself away.

In a collection it works best as the centrepiece of a very large marine aquarium stocked with active fish, and it should be one of the last fish added rather than the first. OATA names angelfish, damsels and some butterflyfish as good company for tangs; shy species and tangs that look like it are the ones to leave out. Corals and invertebrates need separate thought, which the compatibility section covers.

Before ordering, check three things: that your aquarium is marine, fully matured and large enough for a 38 cm adult; that none of the fish already living in it are shy species or tangs of a similar look; and that someone will be at home to receive the parcel. The care and compatibility sections explain each point in turn.

Is your aquarium ready for one?

Meerwasser-Lexikon, a German marine aquarium encyclopedia, rates Acanthurus lineatus as suitable only for experienced keepers. That rating follows from five demands the fish makes at once, and each one deserves an honest answer before you buy.

• Space. A 38 cm adult that swims almost continuously needs a long, open aquarium. Meerwasser-Lexikon recommends at least 2,500 litres for this species and describes its litre figures as a rough starting point, because décor, total stocking and free swimming space all change the real answer.
• Consistently clean marine water. OATA warns that tangs can be stressed by even the smallest amounts of ammonia and nitrite, which may lead to disease. A newly set-up aquarium is not the place for this fish.
• A steady supply of algae. It is a daytime grazer and needs algae-rich food every day, with something left in the aquarium to pick at between meals.
• Room to be territorial. On the reef a large male controls a feeding territory and a harem of females. In an aquarium, tangs can be territorial and may bully new additions, which is why look-alike tangs are kept apart and similar-shaped ones are added together.
• Safe handling. The spines on each side of the tail base are venomous and can cause painful wounds, so routine maintenance has to be planned around them.

If you already run a large, mature marine system and can meet all five, the Lined Surgeonfish rewards the effort: a constant, colourful patrol of open water that brings the movement of a shallow reef into the room. If any one of the five is uncertain, it is better to wait until it is settled than to buy the fish and hope.

Aquarium size and layout

How much space

Aquarium volume is the first decision, and for a large tang it is the one that matters most. OATA's care sheet for tangs and rabbitfish recommends at least 300 litres for a single individual under 20 cm and states that larger and more active species need a larger aquarium. The Lined Surgeonfish grows to 38 cm and FishBase describes it as almost continually in motion, so the 300-litre figure does not describe what it needs. Plan around the species figure of at least 2,500 litres instead, and treat that as a starting point rather than a generous allowance.

Because it is almost always moving, give it as much open length as the aquarium allows, with a clear swimming lane from one end to the other. OATA's general advice to buy an aquarium as large as possible carries real weight here: extra volume gives this fish room to cruise and gives its tank-mates room to keep out of its way.

Layout and equipment

OATA's tang sheet sets out the essentials:

• Filtration. A filter is essential: live rock with sufficient water flow, an internal or external filter, or a sump-based system. A protein skimmer can be beneficial.
• Rockwork. Live or artificial rock provides cover. Keep it compact enough to leave the open swimming lane free.
• Substrate. A thin layer of coral sand, around 2 cm deep.
• Water movement. Moderate flow that keeps the surface moving well.
• A lid or cover. Essential, because tangs can jump, especially when startled.
• Heating. A heater is required to hold the temperature range in the water table below.
• Lighting. Overhead lighting gives a day and night cycle; OATA notes it does not need to be particularly bright for tangs alone.
• Position. Away from draughts, heat sources and direct sunlight, and away from loud noise and vibration.

The wild habitat is worth knowing, but it is not a blueprint. The species is common in surge zones on exposed seaward reefs, and adults are often found in shallow gutters, while juveniles keep to shallow rubble. In the aquarium, OATA's moderate flow with good surface movement is the target, together with open swimming space; there is no need to recreate breaking surf.

Marine water values

The Lined Surgeonfish is a coral-reef fish and needs properly mixed, stable salt water. The table gives OATA's water requirements for tangs and rabbitfish. OATA describes them as a general guide for this group of fish, not a species-specific optimum, and notes that some values need adjusting in a reef aquarium.

Two points are worth spelling out. First, the hardness value is carbonate hardness in dKH, the measure of the water's buffering capacity, not the general hardness (dGH) figure quoted for many freshwater fish. Second, FishBase records the species in tropical water of 24–30 °C on the reef. That is the range the fish meets in the wild, not a target for the aquarium, so hold the aquarium within OATA's 24–26 °C.

Testing and tools

Measure these values rather than estimating them. OATA suggests testing ammonia, nitrite, nitrate, pH and carbonate hardness every week and keeping a regular eye on salinity. Our guide to aquarium water parameters and what to test explains what the common tests measure and why each reading matters, and the water parameter matcher lets you compare your own readings with a stated range such as the one above. Note each result with the date, so a slow drift in pH, KH or nitrate shows up in your records rather than in the fish.

Filtration, maturation and weekly care

Mature the system first

Fish release ammonia, which is toxic. The RSPCA explains that a working biological filter grows beneficial bacteria that convert ammonia to nitrite, which is also toxic, and then to nitrate, which is safer. Those bacteria take time to build up, and a tang that can be stressed by even small traces of ammonia and nitrite should only go into a system where both read zero consistently, over repeated tests.

Our step-by-step guide to setting up and maturing a first tropical tank explains how a filter matures before any livestock goes in. It is written around freshwater set-ups, so take the maturing principle from it and the salinity and other marine values from the water table on this page.

A weekly routine

1. Test ammonia, nitrite, nitrate, pH and carbonate hardness, and check the salinity.
2. Make a 25% partial water change at least once every week, using salt water prepared to the aquarium's temperature and salinity.
3. Rinse filter media in water removed from the aquarium, not under the tap.
4. Clean the protein skimmer regularly so it keeps working efficiently.
5. Top up evaporation with reverse osmosis water. Evaporation removes water and leaves the salt behind, so topping up with salt water would push the salinity upward.
6. Check that the heater is holding 24–26 °C and that the lid is still secure.

The testing, water-change, filter-media, skimmer and top-up steps come from OATA's tang sheet; treat them as the minimum routine. Keep ammonia and nitrite at zero throughout; if either appears, find the cause and put it right before you add more food or more fish.

Feeding an algae grazer

In the wild the Lined Surgeonfish is a daytime grazer. Wikipedia notes that most of its diet is algae, grazed during the day, and FishBase describes it as herbivorous but also taking crustaceans. In an aquarium that translates into a menu weighted heavily towards algae, with a smaller share of meaty food.

What to offer

• Algae-rich foods, most of the time. OATA lists nori sheets, algae-based flake and grazing tabs. Its tang sheet also warns that tangs without enough algal food may become ill.
• Small meaty frozen foods alongside. Mysis shrimp, enriched brine shrimp or krill.
• Variety. Meerwasser-Lexikon's food list for the species is similar: brine shrimp nauplii and adults, flake food, larger frozen foods, krill, mysis, nori and zooplankton.

How often and how much

OATA's routine for tangs is to feed only what the fish can eat within a few minutes, twice a day, and to leave algae sheets or grazing tabs in the aquarium for longer so the fish can graze between meals. Do not overfeed: uneaten food adds to the waste the filter has to process, and this is a fish that tolerates poor water badly.

A clip holds a nori sheet in place while the fish grazes, and offering it at a similar time each day makes it easy to see how quickly it disappears. A settled grazer works at the algae with obvious interest; a fish that ignores food it usually takes is a signal to test the water. Because tangs are active fish and should not share an aquarium with shy species, also check at each meal that every fish in the aquarium is getting its share.

The venomous tail spine

Tangs carry sharp, modified scales near the tail that OATA likens to a scalpel. FishBase describes the Lined Surgeonfish's version as a long, lancet-like spine on each side of the tail base that folds into a deep horizontal groove, and records it as venomous, able to cause painful wounds. Wikipedia likewise describes this species' spines as venomous and capable of wounding handlers.

Working safely around it

• Know where the fish is before your hands go into the water, and move slowly.
• Never try to catch or hold it by hand. OATA advises taking care whenever tangs are handled, because the spine can injure people.
• Follow OATA's best practice and put a sign on the front or lid of the aquarium warning that a hazardous species lives in it, especially if children or visitors might reach in.
• Treat any cut from the spine as a venomous wound and get medical advice rather than dismissing it as a scratch.

Most of the risk comes during maintenance and whenever the fish has to be caught or moved, so plan both with the spine in mind. A long-handled tool for scraping glass or moving rock keeps your hands out of the water for many routine jobs.

A checklist before you order

Everything this fish needs has to be in place before it is ordered, because none of it can be improvised once the fish is in the house. Work through the list and tick each line honestly.

• A marine aquarium of at least 2,500 litres, with a long, open swimming lane and live or artificial rock for cover.
• A filter that has fully matured, with ammonia and nitrite reading zero on repeated tests.
• A protein skimmer, which OATA describes as beneficial for tangs.
• A heater able to hold 24–26 °C, and a lid or cover with no gaps a startled fish could clear.
• Test kits for ammonia, nitrite, nitrate, pH and carbonate hardness, plus a way to measure salinity.
• A supply of reverse osmosis water for topping up evaporation, and enough prepared salt water for the weekly 25% change.
• Nori sheets, algae-based flake or grazing tabs, and small frozen foods such as mysis or krill.
• A stocking plan with no shy species and no look-alike tangs, in which the Lined Surgeonfish is one of the last additions.
• A warning sign for the front or lid of the aquarium.
• Someone at home on delivery day, ready to if practical, film the unboxing.

If every line is ticked, you are ready. If one is missing, sort it out first: a fish of this size and sensitivity is far better served by a system that was ready before the order was placed.

Arrival day and the first weeks

Your fish is hand-bagged in pure oxygen and packed in an insulated poly box, with a heat pack when the weather calls for it, then carried by a tracked, licensed live-animal courier. We email the tracking number and your confirmed delivery date. The full terms are on our delivery and Live Arrival Guarantee page, and the steps below follow them.

On arrival

1. Be at home on delivery day. Live fish cannot be left unattended, and the guarantee needs someone at the address to receive the parcel.
2. Before anything is opened, if practical, start a continuous unboxing video that shows the parcel still sealed, with the outer box visible.
3. Keep filming in one take while the parcel is opened, until the fish can be seen inside its sealed bag.
4. Float the bag in the aquarium for 20–30 minutes so the fish acclimatises slowly.
5. Release the fish without pouring the bag water into your tank.
6. If anything has gone wrong, contact us the same day by email with your order number and clear photos or an optional video, and we will review your claim under our Live Arrival Guarantee and arrange the appropriate replacement or refund.

The Live Arrival Guarantee also requires the parcel to be opened and inspected on the day it arrives; clear photos are accepted and an unboxing video is optional. We strongly recommend an unboxing video when practical: it helps us investigate arrival concerns faster, resolve them with less back-and-forth and understand packing or transit issues so we can reduce recurrence. Video is optional and clear photos are accepted. Never delay necessary animal care to record evidence.

The first weeks

Close the lid as soon as the fish is released, since tangs can jump if startled. Offer algae foods from the first day and watch how the fish swims, breathes and feeds, using the health signs in the next section as your checklist.

OATA also notes that quarantining new livestock for at least a week can reduce the risk of disease. That is general keeper guidance. If you use a separate quarantine aquarium, follow the same arrival steps with it, match its salinity and temperature to the display, and make sure it gives a fish of this size room to swim.

Health, sexing and breeding

Signs of a healthy fish

OATA's tang sheet describes a healthy fish as having:

• clear, bright eyes;
• undamaged fins and intact scales;
• no ulcerations or bumps on the body;
• swimming that is normal for the species, which for this fish means steady, almost constant movement;
• steady breathing.

What normal looks like

A healthy Lined Surgeonfish spends most of the day out in the open, swimming steadily and grazing. FishBase describes the species as active by day and almost continually in motion, so a fish that hides for long periods, hangs in one spot or stops grazing is behaving out of character and deserves a closer look.

Feeding time is the easiest moment to run through the list above every day, because the fish comes into view and you can see it eat. When something changes, test the water before anything else, since any ammonia or nitrite is the first thing to rule out with a tang. Then check that the fish has been grazing on its algae foods.

Sexing and breeding

OATA notes that tangs are very difficult to sex unless they are in breeding condition, and that breeding in the home aquarium is unlikely. In the wild the species forms spawning aggregations, according to FishBase. Treat the Lined Surgeonfish as a display fish to enjoy for its colour and movement rather than as a breeding project.

Keep one per aquarium

On the reef the Lined Surgeonfish has a complicated social life. FishBase describes a territorial species in which a large male controls well-defined feeding territories and harems of females, while adults usually form schools, are commonly found in shallow gutters and gather in large numbers to spawn. Juveniles are solitary and secretive on shallow rubble.

A home aquarium cannot offer that kind of space. OATA's advice for tangs is that shoals can be kept only in an aquarium large enough for them, with at least six of the same species to spread aggression, and that tangs which cannot be kept in such a group should be kept singly to avoid bullying of smaller or less dominant fish. For a species that reaches 38 cm and needs around 2,500 litres on its own, a group of six would need space on a scale few private aquariums can offer, so the practical choice is a single Lined Surgeonfish.

Do not add a second one later or buy two as a pair. Two fish of the same shape and pattern competing for the same grazing space is exactly the combination OATA warns against.

Choosing tank-mates

OATA's tang sheet gives short, practical compatibility advice, and it applies directly to this species.

The last two rows cover different things. Overall appearance, the colour and pattern a fish shows, decides whether two tangs can share an aquarium at all. Body shape decides the order: tangs of a similar outline that are going to live together should arrive together.

Checking an existing community

If the Lined Surgeonfish is joining an established aquarium, look at the current residents with those rules in mind:

• Is any resident shy or easily kept away from food? If so, this is the wrong addition.
• Does any resident tang share its colour and pattern? Two look-alike tangs should not be mixed.
• Is there already a tang of a similar body shape? OATA advises adding such tangs together, so a newcomer joining a settled one works against that advice.
• Will the aquarium still give everyone room once this fish reaches its adult 38 cm?

Stocking order

OATA advises adding tangs towards the end of stocking, because they can be territorial and may bully new additions. Add the Lined Surgeonfish after the rest of the community is established, so that it arrives as the newcomer rather than defending ground against later arrivals.

Corals and invertebrates

We make no reef-safe or invertebrate-safe promise for this fish. It is mainly an algae grazer, but FishBase notes that it also takes crustaceans, and OATA points out that some water values need adjusting in a reef aquarium. If you keep corals, shrimps or crabs, plan the mix with that in mind and be ready to separate animals if problems appear.

Every combination still depends on individual temperament and aquarium size, so watch the first days after any introduction closely, especially at feeding time.

Common questions

How big does a Lined Surgeonfish grow?

FishBase records a maximum length of 38 cm total length, with 25 cm given as a common length, and Wikipedia and Meerwasser-Lexikon also put the adult at about 38 cm. Plan the aquarium for that adult size, not for the size of the fish when it arrives.

What size aquarium does it need?

Meerwasser-Lexikon recommends at least 2,500 litres for the Lined Surgeonfish and treats that figure as a rough starting point. OATA's 300-litre recommendation covers only a single tang under 20 cm, so it is far too small for this species. A secure lid is essential because tangs can jump, especially when startled.

How many should I keep together?

Keep one. The species is territorial, and in the wild a large male defends a feeding territory and a harem of females. OATA advises that tangs kept as a group need at least six of the same species in an aquarium large enough for them, and should otherwise be kept singly to avoid bullying. For a fish that reaches 38 cm, a single specimen is the practical plan.

Is the Lined Surgeonfish suitable for beginners?

No. Meerwasser-Lexikon rates it as suitable only for experienced keepers. It needs a very large, fully matured marine aquarium, consistently clean water, an algae-rich diet and careful handling because of its venomous tail spines.

What does a Lined Surgeonfish eat?

It grazes algae through the day and also takes some crustaceans in the wild. Offer algae-rich foods such as nori sheets, algae-based flake and grazing tabs, with small meaty frozen foods such as mysis, enriched brine shrimp or krill. Feed what it eats within a few minutes twice a day, leave algae sheets and grazing tabs in for longer, and avoid overfeeding.

What temperature and pH does it need?

OATA's group guidance for tangs is 24–26 °C, pH 7.9–8.3 and a specific gravity of 1.020–1.025, with zero ammonia and nitrite and carbonate hardness of 8–12 dKH. These values apply to tangs as a group; FishBase's 24–30 °C describes the wild reef, not an aquarium target.

Is the Lined Surgeonfish aggressive, and is its spine dangerous?

It is territorial and may bully new additions, so add it towards the end of stocking and avoid tangs that look similar to it. Each side of the tail base carries a long spine that FishBase and Wikipedia describe as venomous and able to cause painful wounds, so take great care whenever your hands are in the aquarium.

Which fish can live with it?

OATA names angelfish, damsels and some butterflyfish as good tank-mates for tangs. Avoid shy species and tangs that look too similar; if you plan more than one tang with a similar body shape, add them at the same time and towards the end of stocking. Aquarium size and individual temperament still decide whether a particular mix works.

How does a Lined Surgeonfish arrive alive in the UK?

It is hand-bagged in pure oxygen, packed in an insulated poly box with a heat pack when the weather calls for it, and carried by a licensed live-animal courier. Someone must be at home to receive it. If practical, film a continuous unboxing video from the sealed parcel to the fish still in its bag, float the bag for 20–30 minutes, then release the fish without pouring the bag water into your aquarium. If anything is wrong, contact us the same day with your order number and clear photos or an optional video.

Sources and further reading

• OATA: How to look after tangs and rabbitfish. The UK ornamental aquatic trade association's group care sheet, used for water values, set-up, maintenance, feeding, handling and compatibility.
• FishBase: Acanthurus lineatus. Species summary for adult length, range, wild habitat, behaviour, diet and the venomous tail spine.
• Wikipedia: Acanthurus lineatus. Natural history, alternative common names, diet and the venomous spines.
• Meerwasser-Lexikon: Acanthurus lineatus (in German). Experienced-keeper rating, a rough aquarium size and a food list for the species.
• World Register of Marine Species: Acanthurus lineatus. Accepted scientific name and family.
• RSPCA: fish environment. General welfare guidance on filtration and the breakdown of ammonia, nitrite and nitrate.

Our delivery and Live Arrival Guarantee terms are linked in the arrival section of the care guide above.