The Twotone Tang or Brown Sailfin Tang is very hardy and a super algae grazer, a great addition to a reef aquarium!

   Another very popular tang that is very hardy and very inexpensive is the Twotone Tang. It really lives up to its name in its juvenile coloration (see picture below), and as an adult it often looks like a browner version of its close relative the Yellow TangZ. flavescens. It is also readily identified as the Brown Sailfin Tang or the Scopas Tang by aquarists, with its general coloration being yellowish brown with tiny pale blue dots all over. Sometimes it is even all yellow like the Yellow tang, and on rare occasions there are mutations with several different color splotches across the fish. Because this tang develops an oval bristle-like patch known as setae just in front of the peduncular spine, it is also sometimes called the Brushtail Tang.

   The Twotone Tang makes a wonderful addition to the marine aquarium, especially a community aquarium. It is relatively peaceful but its behavior is not quite as amiable as the Yellow Tang, this tang will claim and defend a territory. Generally it will get along with a wide variety of tank mates, but is best kept singly as it does not mix with others of its genus. Bold in nature, it will quickly adapt to aquarium fare and is easy to care for once it is settled. One of the hardiest of the surgeonfish, it is highly disease resistant in a quality environment and responds well to treatment.

   There are some things that the Zebrasoma species have in common with all the surgeonfish and tangs. They like plenty of water movement to provide an oxygen rich environment rather than a placid aquarium. They are quick and agile swimmers so will need lots of swimming space along with plenty of crevices among corals/ rocks to retreat into and for sleeping at night. Being voracious algae eaters, an aquarium with good algae growth will provide for their nutritional needs as well as making them excellent candidates for a reef environment.

For more Information on keeping marine fish see:
Guide to a Happy, Healthy Marine Aquarium

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Perciformes
  • Family: Acanthuridae
  • Genus: Zebrasoma
  • Species: scopas
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Habitat: Natural geographic location:

   The Twotone Tang or Brown Sailfin Tang was described by Cuvier in 1829. They are found in the Indo-Pacific from east Africa to Japan and Tuamotu.
   In their natural habitat they are found at depths between 3 to 197 feet (1 – 60 meters) in lagoons and outer reefs. They inhabit areas of dense coral and occur singly, in pairs or in small groups, even forming schools in some locations. Juveniles are solitary and very secretive, hiding among the corals.
   It is very similar to its close relative the Yellow TangZ. flavescens, which has an all yellow body with a white peduncle spine. These two species co-occur and interbreed in Micronesia and southern Japan. As they co-habitat in many areas and behave the same, it has not been ruled out that the Z. flavescens may actually be a xanthic form of theTwotone Tang, or possibly a geographic variant.


   These fish are not listed on the IUCN Red List.


   The Twotone Tang or Brown Sailfin Tang has a disk like shaped body similar to all surgeonfish, but with large dorsal and anal fins. When the fins are fully extended, the total height of these fish is about the same as the length. Like all the sailfin tangs, they have a slightly extended snout. The general coloration is dark yellowish brown with pale blue squiggly or dotted horizontal lines. They can be quite variable in color; they can be almost black looking, to brownish or yellow, and on rare occasions there are mutations with several different color splotches across the fish.

Picture of a juvenile Twotone Tang, Zebrasoma scopas
Juvenile specimen
Photo © Animal-World: Courtesy Greg Rothschild

   In all color variants, a common characteristic is a single white spine or “scalpel” on each side of the caudal peduncle. This spine is used for defense or dominance in defending a territory. When not in use the spine is folded down into a groove. Caution needs to be exercised when handling surgeonfish as a cut from its scalpel can cause discoloration and swelling of the skin with a high risk of infection. The pain lasts for hours then still ends up having a dull ache.
   There is an oval bristle-like patch known as setae just in front of the peduncular spine. This patch is not found on juveniles less than 2.8 inches (7 cm).
   Juveniles are more colorful than adults, and the name ‘Twotone Tang’ is derived from the juvenile coloration. Their color has lots of yellow usually on the front half of the fish and it is usually comprised of thin vertical bars and spots.

Length/Diameter of fish:

   Adults reach 6.7 inches (17 cm).

Maintenance difficulty:

   The Twotone Tang is a great addition to the marine aquarium as it is very hardy and easy to keep. This fish can handle just about any challenge in the marine environment except for poor water quality. Even so it will do best in an environment that provides consistency, not only in water conditions and quality, but also in decor and fellow inhabitants. It can be housed in a fish only tank or in a reef environment as it will not harm corals or invertebrates. It is highly disease resistant and responds well to treatment when ill.
   There are some Acanthuridae members that are delicate and will require more specific care, but most will respond well if you employ a few technical considerations. All surgeonfish need an aquarium with plenty of aeration, a strong current will help to provide good oxygenation. Provide plenty of space, especially for adult specimens, along with lots of rocks/ corals with crevices for retreating and for sleeping. This decor will also lend itself to algae growth which surgeonfish enjoy grazing on, making them a valuable addition to a reef environment.
   Surgeonfish and tangs are continuous feeders and they need to be provided a proper diet. They are susceptible to nutritional disorders which may cause color loss and LLD (lateral line disease). Supplementing their diet with the addition of vitamin C to their food or adding a vitamin supplement directly to their water can help to avoid or aid in reducing these ailments. They are also susceptible to bacteria resulting from organic buildup which deteriorates water quality. Consequently they will need vigorous filtration, protein skimming, and regular small water changes.
   Many of the Acanthuridae members are very colorful, active, and attractive to aquarists. But they do not produce as much skin mucus on their bodies as other fish and can be susceptible to diseases such as Marine Ich and Marine Velvet. Surgeonfish are definitely a candidate for quarantine when you first receive them. They can be treated successfully with medical care or copper drugs, but because they have an important microfauna in their digestive system, prolonged or continuous use of a copper treatment is not advisable.
   In the wild a cleaner wrasse (Labroides sp.) will help them by taking parasites from their bodies, however these wrasses are extremely difficult to sustain in captivity. Alternative fish such as Neon Gobies (Gobiosoma sp.) or cleaner shrimp can help them by providing this cleaning service in the home aquarium.


   The Twotone Tangs are primarily herbivores. In the wild they feed mainly on filamentous algae which they scrape from hard surfaces. This genus can store fat in their body cavities so may go through periods of non-feeding.
   In the aquarium the majority of their intake will be vegetable matter, but they do need some meaty foods as well. Provide lots of marine algae, prepared frozen formulas containing algae or spirulina, frozen brine and mysid shrimp, and flake foods. Japanese Nori or other seaweed can be adhered to the aquarium glass with a vegetable clip. An occasional live rock with micro and macro organisms will be greatly appreciated. Culturing macro algae like chaetomorphia in the tank is also a great idea. Feed 3 times a day in smaller amounts instead of a large quantity once a day. As continuous grazers, they will benefit from this and it will also keep the water quality higher over a longer period of time.
   Providing a vitamin supplement (including vitamin C) can help provide for their nutritional needs, and vitamin C can help prevent or reduce Lateral Line Erosion (LLE). This can be done by soaking dried pellets with liquid vitamins, adding vitamins to the food, or adding a liquid vitamin into the water. It is also said that pellets soaked in garlic may help fend off Marine Ich. Some hobbyists also report success with supplemental foods such as previously boiled or frozen zucchini, broccoli, spinach, and leaf lettuce.


   A quick and agile swimmer it will spend a good deal of its time in the open water and moving in and out of crevices. Frequent water changes are not necessary, rather normal water changes at 10% biweekly or 20% monthly are fine.
   For more information see, Marine Aquarium Basics: Maintenance

Aquarium Parameters:

   All surgeonfish/ tangs are quick agile swimmers and need lots of open areas. To feel secure they also need rocks/ corals with many nooks and crannies to hide in and to wedge themselves into at night for sleeping. This fish will not bother corals or inverts but it will graze on algae, so it highly useful in a reef environment. However keep corals glued down, as their quick speeds may topple a coral or two. They thrive well in tanks with algae growth.
Minimum Tank Length/Size:
   A minimum 75 gallon (284 liters).
Light: Recommended light levels
   It nature it is found in sunlit areas. It can be kept under normal lighting conditions in the aquarium, but can also be kept under very bright light as long as some dimly lit spaces are provided.
   This species lives in tropical areas. Temperatures between 74 -82° F (23 – 28° C) will serve them well.
Water Movement: Weak, Moderate, Strong
   All surgeonfish and tangs thrive with good water movement, need lots of oxygen, and love to have the water rushing over their gills at times. Provide strong movement in at least one area of the tank.
Water Region: Top, Middle, Bottom
   It will spend time in the open water and darting in and out of the rocks/ corals. It will sleep in crevices at night.

Social Behaviors:

   The great thing about the Twotone Tang is that they are fine in a reef setting with inverts and corals, and they will graze on the algae. It is relatively peaceful but its behavior is not quite as amiable as its close relative the Yellow Tang, this tang will claim and defend a territory. Generally it will get along with a wide variety of tank mates, but is best kept singly as it does not mix with others of its genus.
   Surgeonfish and tangs can be territorial, sometimes just with their own kind and sometimes with other species. Introducing a new surgeonfish into an aquarium that already houses one or more is usually a problem. It is best to initially introduce several species together rather than adding a new one later on. Though a large aquarium can help alleviate many problems, be aware of the social behaviors of any species you are considering to prevent compatibility problems.
   You may successfully pair this tang with different genus’ as long as there are no similarities. One example of mixing genus in a large tank without incident would be to house a Naso Tang, Yellow Tang, and a Hippo Tang Adding them together initially works best. When adding a new member to an established group, changing the rock work will often alleviate any aggression to the “new guy”. A little chasing will occur, but usually nothing detrimental.

Sex: Sexual differences:

   For most of the Zebrasoma species there is no sexual differences noted, but for this species the males have some slight differences. They tend to be larger than the females and the bristle-like patch of setae just in front of the peduncular spine is longer on the male. The male may also have a noticeable color change when spawning.


   Some species of surgeonfish have spawned in public aquariums and there have been a few scattered reports of spawnings in home aquariums, but regular spawnings and the rearing of the young has not yet been reported. Though the Twotone Tang has not yet been bred in captivity, this species has been observed in group spawning as well as pair spawning in the ocean.
   For information on breeding and the development of the fry, see: Marine Fish Breeding: Tangs.


  The Twotone Tang or Brown Sailfin Tang is readily available at retailers and is inexpensive. They are priced at about $18.00 USD and up.