Orange Shoulder Tang Care: Acanthurus olivaceus

There isn’t much question about where the orange shoulder tang got its name – provided you’re looking at an adult. Juveniles, however, slide under the radar or even get mistaken for another fish entirely. Youngsters sport vibrant yellow scales with a touch of blue to the anal and dorsal fins. You don’t see even a hint of the orange slash on the shoulder. That doesn’t start to appear until the fish matures. The slash appears around the time they hit 2.5-3 inches (6.4-7.6cm) in length. It’s also when you see that yellow shade change to a duskier tone.

Adult orange shoulder tangs have a grayish-blue or brownish-olive tone to their bodies, though they retain the blue highlights on their fins. And, of course, they have the deep orange slash trimmed in purple-black on their shoulders. They aren’t as bright or dazzling as some tang species, but they still manage to stand out against a healthy reef display. And if you catch them under the proper lighting? The two-tone gray turns a perfect shade of silver.

Orange Shoulder Tang Lifespan

You can find orange shoulder tangs throughout the Pacific. They stretch from Hawaii to the East Indies, darting in and out of the surge zones of their favorite reefs. The only time you see them leave? When a cyclone (the Pacific’s term for a hurricane) comes through and churns up the reef’s water, filling it with sediment.

These large members of the surgeonfish group are accomplished grazers on the reef, demanding healthy reef systems. Along their preferred territories, scientists have recorded some individuals surviving for up to 35 years! Of course, life in captivity presents definite challenges for the orange shoulder tang. And a lifespan of 5-10 years is a little more realistic within an aquarium setting.

The age (and size) of an orange shoulder tang determines where you’ll find it as you cruise from Hawaii to Polynesia and Micronesia. The smaller, yellow juveniles cling to the shallow, sandy reefs. As they grow and age, they move out to the higher oxygen levels of that surge zone. Plankton rolls in through the water in significant numbers within the turbulent waters, coming up from the depths with the changing tides. The coral also provides plenty of grazing territory – not to mention potential retreats from predators cruising the drop-off.

Duplicating a surge zone within a home aquarium isn’t the most straightforward task in the world. And that’s one reason you often find the orange shoulder tang in commercial settings. But if you have powerheads in at least one spot within your tank, you’ll do fine. This sets up an “exercise” area where they can swim against the current, replicating natural behaviors. And it won’t put a strain on the rest of the fish and invertebrates in your tank, which may not appreciate a high flow rate.

And while they are on the large side, they’re prone to spooking. A cave or crevice they can wedge themselves into is essential. This is also where an orange shoulder tang will sleep at night. You need to take care that your structures provide room for the fish to do so as juveniles AND adults. Otherwise, your tang will grow stressed.

Orange Shoulder Tang Tank Size

As an adult, the orange shoulder tang can reach up to 14 inches (35.6cm) in length. They’re not the largest of the group (that honor goes to the sailfin), but you still need to plan for that cute yellow juvenile to grow into a hefty monster. And if you go too small? You’re going to cope with aggression problems.

At an absolute minimum, you’ll want a tank of 135 gallons (511L). But if you’re going to keep your orange shoulder tang living for its entire lifespan, go up to 180 gallons (681L) and a total of 6 feet (1.8m) in length. This will provide the swimming space the tang requires. You’ll also have the room to stock live rock for algae to grow and supplement your orange shoulder’s diet.

Then you can set up your powerhead in one portion to supply a healthy current. You only need it in one part of the tank, and you can choose any height to suit the needs of your corals or sea anemones. Orange shoulder tangs will swim throughout every level of an aquarium, and as long as they get a strong current SOMEWHERE, they’ll stay happy.

Are Orange Shoulder Tangs Reef-Safe?

The orange shoulder tang is an omnivore, leaning heavily on the algae side of the menu. This makes them reef-safe – in theory. And as long as you keep them properly fed and choose a tank of an appropriate size (without overstocking), you shouldn’t see them bothering your corals, clams, or other invertebrates.

The trouble comes in if you fail to provide enough food. Hungry orange shoulder tangs will start picking at corals, potentially resulting in harm to the polyps. And if you have a tight space with other fish that feed on algae and detritus in the tank? You’ll set up conditions for competition and aggression. This can lead to your orange shoulder tang turning on your reef.

Orange Shoulder Tang Diet

Orange shoulder tangs are specialized omnivores. They feed on filamentous algae, diatoms, and detritus they pick up from the sand. This is why it’s so important to balance your décor between open sand and live rock. You’re providing ample opportunities for them to find a little bit of everything on their menu.

But at the top of the list? Algae. Without SOME amount of algae in their diet, you’re going to end up with problems. Keeping a patch of algae growing in your tank solves the problem nicely, but the amount they’ll scavenge won’t sustain them (probably not, anyway – unless you have a major algae problem in your tank). That means looking for additional sources to keep them healthy:

• Dried marine origin algae
• Nori on a veggie clip
• Spirulina-based commercial foods

You want to incorporate algae supplementation into their diet at least three times a week. You’ll boost their immune system, prevent potential aggression problems, and keep your orange shoulder tang looking its best.

Compared to most tang species, the orange shoulder tang is a dream come true. They’re not aggressive with one another (more on that in a second), and they’ll tolerate sharing an aquarium with other surgeonfish. You need to take care of the order in which the fish go into the tank, but you don’t need to worry about fights breaking out once they settle. It’s one reason orange shoulders are so popular.

Except for convict tangs and gold-rimmed tangs, make sure you add your orange shoulder tang to the tank FIRST. This gives them the chance to settle in, choose their bolt holes, and set up the grazing patches they want. The two exceptions come out even MILDER than orange shoulders in terms of temperament, so they should go into the aquarium first. You’ll also want to double that ideal tank size to 300 gallons (1136L) to prevent potential bullying by the orange shoulder.

If you plan to house more than one orange shoulder tang, introduce them to the tank simultaneously. It doesn’t matter if you have two fish of different ages. You can keep a juvenile and an adult together without a problem. The most important part is allowing them to adjust to the new environment at once. Otherwise, you might see bullying appear.

The orange shoulder tang exists alongside plenty of other fish. You’ll need to keep them well-fed, of course, but they don’t pick on their tank mates as some of their cousins might. That gives you plenty of options for setting up a colorful community reef tank:

• Anthias
• Assessors
• Blennies
• Clownfish
• Damselfish
• Dartfish
• Dottybacks
• Dwarf angelfish
• Gobies
• Mandarins
• Wrasses

Telling a male orange shoulder tang from a female gets tricky. There’s a slight size difference, with females edging out their male counterparts. And during spawning season, males develop a brighter color palette. But that’s about it. The two remain identical (for the most part).

This isn’t much of a problem, though, as captive breeding has yet to succeed. Similar to other surgeonfish, orange shoulder tangs are broadcast spawners. Following the courtship ritual, the female releases her eggs close to the surface. The male follows close behind, fertilizing the eggs as they rise. The eggs then drift on the ocean current, developing as part of the plankton. And it’s the plankton that serves as the fry’s first meal. As the baby orange shoulders grow and move close to land, they drop into the calmer portions of the reef within sheltered bays and lagoons.

Duplicating these conditions in a home aquarium is almost impossible. So while you CAN successfully keep a pair of orange shoulder tangs, getting the eggs and fry to survive is another story. This is one reason you may find yourself spending a little extra for your fish, as they require wild collection.

While the orange shoulder tang lacks dynamic coloring (except for that slash), they’re active members of a reef community. That’s enough to recommend them for any aquarist – provided you think about ALL aspects of their care.

Pros

• The orange shoulder tang isn’t as aggressive as other surgeonfish.
• While dependent on algae in their diet, you can supplement them with spirulina or other dried marine-based algae.
• Orange shoulder tangs will tolerate sharing an aquarium with other tang species.

Cons

• As of now, the orange shoulder tang doesn’t get bred in captivity.
• Orange shoulders commonly develop marine ich.
• While smaller than other scalpels, a wound from your orange shoulder tang can lead to a severe infection.

The orange shoulder tang combines size, personality, and a touch of color into the perfect reef tank addition. But if you need that last little bit of convincing, we’ve got you covered.

This YouTube video shows an orange shoulder tang enjoying the open swimming space in its tank:

Want to know about some of the best orange shoulder tang tank mates?

You like the orange shoulder, but you’re interested in a more vibrant tang. No problem:

Conclusions

The orange shoulder tang isn’t the biggest or even the brightest member of the surgeonfish family. They’re not even the calmest. But coming out somewhere in the middle for each of those categories? That can be a good thing. It makes them easy for almost anyone to handle. And a tang zooming around your tank, nipping away at pesky algae? Well, who doesn’t need that?

References

• Froese, R. and Pauly, D. 2005. “Acanthurus olivaceus.” FishBase.
• Michael, S.W. 2001. Marine Fishes, 500+ Essential to Know Aquarium Species.