Brown surgeonfish

Lavender Tang ~ Dusky Surgeonfish<br /> Spot-Cheeked Surgeonfish ~ Blackspot surgeonfish

Family: Acanthuridae Picture of a Brown Surgeonfish or Lavender Tang, Acanthurus nigrofuscusAcanthurus nigrofuscusPhoto © Animal-World: Courtesy David Brough
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Surgeon fish are the only fishes with the shortest tail. Maybe one day they can become bigger and live better life.  Aujanique S. Glenn

   The Brown Surgeonfish is the smallest and least colorful of its genus, but makes up for this by its more peaceful demeanor with other tank mates!

   Due to its relatively small size, the Brown Surgeonfish or Lavender Tang is a good choice for the home aquarium. This fish along with its close relative the Convict Tang A. triostegus, is one of the more peaceful surgeonfish. Its moderate behavior makes it a good companion in a community tank. It should not be housed with aggressive species but rather more peaceful fish. It can be kept with a variety of tank mates including some of the other genus' of surgeonfish, though it will be aggressive towards others of its own kind.

   Like all surgeonfish and tangs, the Brown Surgeonfish likes a lot of water movement rather than a placid aquarium. A quick and agile swimmer it will need plenty of swimming space, and like all surgeonfish needs corals/ rocks with crevices for retreat and sleeping at night. It will be quite hardy once it gets settled, this can be accomplished by initially offering a good macro algae. Being a voracious algae eater, good algae growth in the aquarium also helps provide for its nutritional needs as well as making it an excellent candidate 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: Acanthurus
  • Species: nigrofuscus
Powder brown tang starring with NEON GOBY (Elacatinus oceanops)
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Neon Goby doing what they do best, cleaning a tang!

This Neon Goby was obviously enlisted during the quarantine period for this Powder Brown Tang. Notice how the tank flares it's fins and stays still. This signals the goby to clean and while the tang periodically moves forward, it quickly backs up again and wants to continue to be cleaned! Neon Gobies do well in tanks as small as 10 gallons up to .... well, ocean size! They will pair up and easily breed in captivity as well! Make sure you have tiny rotifers hanging around!

Brown Surgeonfish, Lavender Tang, Acanthurus nigrofuscus
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Video of Brown Surgeonfish in dealer's tank.

The Brown Surgeonfish is one of the smallest, reaching only about 8.25" and one of the most docile, which the Convict Tang being the most docile of the Acanthurus genus. They are quite placid when housed in the proper minimum tank size of 125 gallons. In a smaller tank, they can develop behavior problems and aggression, which is true of all tangs. Do not house with aggressive or predatorial fish. They are just as at home in a reef as a fish only tank, however providing light for algae growth will go a long way in keeping them happy and healthy!

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Habitat: Natural geographic location:   The Brown Surgeonfish or Lavender Tang was described by Forsskal in 1775. They are found in the Indo-Pacific in the Red Sea, Transkei, South Africa, Tuamoto and Hawaiian Islands.  They are also found in southern Japan, the southern part of the Great Barrier Reef, New Caledonia and Rapa.
   In their natural habitat they are found at depths down to about 65 feet (20 meters). They are rarely seen alone or in pairs, rather they are usually found in groups. Small groups are the norm unless they are in oceanic areas, then they will form large schools for protection. The areas they inhabit are shallow lagoons with hard substrates and seaward reefs in deeper waters, feeding on filamentous algae.
   Juveniles are initially quite wary, hiding in crevices among rubble and rocks, but soon the need for feeding draws them into small mixed groups. Seeking protection in numbers, these groups will consist of surgeonfish and various other like sized fish that will feed on the bottom and roam the edges of shallow reefs. Larger juveniles will begin teaming up with others of their own species.
   Whether they are territorial or not depends on the location. Along with the with Convict Tang A. triostegus they are often a less aggressive surgeonfish, so are on the bottom of the pecking order. The protection of large schools allows them to invade the territories of other herbivores to feed. They sometimes can be seen grazing with a group of Convict Tangs.

Status:    These fish are not listed on the IUCN Red List.

Description:    The Brown Surgeonfish or Lavender Surgeonfish has a disk like shaped body, very similar looking to other Acanthurus species. Though it is the smallest and least colorful species in this genus, it is easily distinguishable by the dull orange spots on the head and the two dark spots at the rear base of the dorsal and anal fins. Its adult coloration varies from a brown to a light grayish brown with a lavender tinge, especially on the fins. When displaying aggression its upper back and the entire dorsal fin lighten, sometimes becoming distinctly yellow.
   It has blackish brown lips, its pale pectoral fins are narrowly edged in black, and sometimes the anal fin is narrowly edged with white. Its caudal fin is lunate (crescent-shaped). On each side of the caudal peduncle is a single spine or "scalpel" used for defense or dominance. When not in use the spine is folded down into a groove that is circled in black. 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.
   Juveniles are brown to bluish black and have orange scribbles on the head that break up into spots as they mature. The lifespan of this species is unknown.

Length/Diameter of fish:    Adults reach 8.3 inches (21 cm).

Maintenance difficulty:    The small size of the Brown Surgeonfish lends itself to being a great addition to the marine aquarium. They are easy to keep as long as there is plenty of algae growth.  Babies under 2" will starve quickly without this abundance of natural greenery. It is generally quite hardy and can handle a wide range of water parameters. However 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.
   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 spp.) or cleaner shrimp can help them by providing this cleaning service in the home aquarium.

Diseases that Surgeonfish and Tangs are susceptible to:
Marine Ich (white spot disease), Marine Velvet
and Lateral Line Erosion (LLE)

Foods:    The Brown Surgeonfish or Lavender Tang are primarily herbivores. In the wild they feed almost exclusively on filamentous algae which they scrape from hard surfaces. 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 2 to 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.

Maintenance:    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 55 gallon (208 liters) for a single tang. Though a smaller tang they are active speed swimmers. Some suggest that any tang should have a 6' long tank minimum, but if this tang is kept singly with no obstructions or overcrowding, a 55 gallon can work.
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 Brown Surgeonfish or Lavender Tang is that they are fine in a reef setting with inverts and corals, and they will graze on the algae. They can also be kept in a fish only community tank with peaceful tank mates. This fish is very peaceful and gets along with most fish, except others of their own genus. Add them first if they will be kept with other tangs. If attempting more than one of this genus, you will need a tank with hundreds of gallons to ward off aggression due to territorial behaviors. Avoid lionfish and groupers as tank mates.
   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.
   At times you may put surgeonfish and tangs together with different genus' as long as there are no similarities. For example a large tank can house a Naso Tang, Yellow Tang, and a Hippo Tang with out incident. 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:    No sexual difference is noted for this species.

Breeding/Reproduction:    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 Brown Surgeonfish has not yet been bred in captivity, this species has been observed performing spectacular group spawnings in the ocean. Usually in the evening these fish will migrate in a single file to their spawning site, sometimes traveling as far as a half a mile. Here they gather as a huge group of hundreds, sometimes thousands of fish milling together in a dome shaped mass. A few fish will break away every few minutes to dart to the surface to release their gametes and then quickly rejoin the protection of the masses. Thousands of eggs are released in a spawning session.
   For information on breeding and the development of the fry, see: Marine Fish Breeding: Tangs.

Availability:    The Brown Surgeonfish or Lavender Tang is often available at retailers and it is possible to order one, though availablility may be seasonal. They are priced around $15.00 USD and up.

Authors: Carrie McBirney and Clarice Brough, CFS
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