Success in a Reef: Surgeonfish (Tang) Compatibility

What’s in a Surgeonfish … Er, Tang?

 Surgeonfishes, or “Tangs”, as they are most commonly referred to, are some of the most vividly colorful and wildly interactive fishes one may choose for their saltwater fish only, or reef aquarium. They maintain some of the most luxurious features and colors, are largely reef safe, live 20-30 years, and are smart enough to learn and recognize their owners. Tangs are some of the most popular fish for these reasons. However, Tangs are fish who know what they want, and what they want is territory. This means that not all Tangs get along, and not all situations are ideal for mixing them. Some Tangs are excessively territorial, while others simply grow too large. There’s a rhyme and reason for all of these quirks and unique characteristics, as well as tips and tricks to overcome them. Together, we’ll discuss the key differences between the most popular Genus of species on the market, and go over some of the most successful ways for mixing and keeping groups them in an aquarium.

 Ok, so what’s the big deal? Aren’t they kind of dumb?

 Tangs are some of the most intelligent species of fish studied to date. They are capable of remembering, marking territory, learning humans, and even predicting behavior. Knowing this, it is very important that we understand their territorial behavior as a need, something we must provide, rather than a behavior to eliminate. Instead, we want to manipulate it. We prefer to indulge the parts of their behavior which are not harmful, such as their need for large aquariums and varied diets of algae, and work around the ones which are, such as their desire to destroy invading Tangs into their territory.

When it comes to mixing Tangs, there are some general rules that, if followed, tend to solve or prevent most of their compatibility concerns, such as fighting. following these general guidelines will yield success for most saltwater aquariums. The rules listed below are the general ways we manipulate their behavior in descending order of importance.

  • Tank size — it is generally recommended that you provide approximately 75 gallons per small-species Tang, with more being ideal. Large species Tangs require at least double this. Young specimen may grow up in smaller systems but this can lead to musculoskeletal development problems and behavioral issues.
  • Genus of classification — selecting a single species from different Genus (Acanthurus, Ctenochaetus, Zebrasoma) yields the safest results when mixing specimen. This is a critically important guideline. Lesser recommendations say to select specimen which differ in body shape and color, but this is too general to be much help. Always go deeper, to the Genus and species. The reason is because, as we all know and (hopefully) understand, Tangs are primarily herbivores. They consume vast quantities of varieties of algae over the course of the entire day on reef. What is less commonly understood is that Tangs have both a mental and a biologically engineered preference for certain types of algae. For example, Ctenochaetus are colloquially referred to as bristletooth Tangs, due to their mouths containing dull bone inserts used for scraping their preferred filamentous algae from rocks. This means that Tangs largely aim to protect their primary food source (as in the wild), and tend to feel less threatened and territorially aggressive towards Tangs of different Genus, which do not compete for the same resources. Another example would be Zebrasoma, which tend to prefer hair-like algae over all else.
  • Timeframe which they were added to the aquarium — the most common misconception with Tangs is that they are said to be aggressive. This is, largely, untrue. While Tangs do have a semi-aggressive nature, they are actually more accurately described as territorial. As you may have noticed, the theme to adding Tangs to an aquarium successfully is managing their territories. Tangs want to claim a portion of your aquarium for themselves. To minimize aggression, the most impressive and capable tool for keeping multiple Tangs together is: adding them to the aquarium at the same time. Because Tangs will claim territory to the fullest extent of their capabilities, they will only cooperate before they’ve claimed area. This means if you place a single Tang into a tank, it will claim the whole tank for itself. If you place two of them, they are likely to divide the space evenly. However, if you allow a Tang to claim a tank as a territory and then add a new one, it is much more likely to be stressful and unsuccessful, because now that new Tang is invading existing territory.
  • Size — Tangs which are added smaller systems (under 200 gallons) generally want to be kept around the same size, to prevent the larger one from bullying the smaller one out of territory. If there are existing Tangs in the aquarium, then the safest bet is to ensure the new Tang is noticeably larger than the existing Tangs. They will not be able to terrorize a larger Tang as easily, and the new Tang will recognize that some territory is already claimed.


A new friend is on their way, what’s the best way to make sure everyone gets along?

 Here are some general tips for adding Tangs to your aquarium. This assumes the system is fully cycled and stable. *Always remember: a well-fed Tang is a well-behaved Tang!

Your first and foremost powerful tool is how and when you add them. Adding all of the Tangs you want to your aquarium at the same time will yield the greatest success rates. On the same note, adding a group of Tangs to an existing group of Tangs is pretty much the only way to safely introduce new ones. Adding single specimen to groups which have well developed territories is a recipe for disaster.

  • Territory is their goal. Tangs want territory. It is not possible to predict how much, or where, but we can predict that they will try to claim some. This is why they fight and nip at others. Rearranging some or all of the rock work in the aquarium will encourage old fish to get along with new fish, as now the environment is different and they have to claim a new territory with the new fish to consider.
  • Size matters. If you’ve got a Tang already, you’ll want to make sure the new one you’re interested in is noticeably larger than the one you’ve got now. A larger Tang will be able to handle the abuse he will receive for invading the territory of your existing Tang. A smaller Tang will have a much harder time.
  • Distractions work. Feeding the aquarium when you add new fish, or turning the lights off for the day, is a good way to minimize the stress of the first day. Remember, it’s an exhausting process to be purchased and moved to a new home. A fish that is given a day to recover before being forced to insert its place in your reef is a fish that is much more likely to survive.

Following one or more of these general guidelines will bring most reefers to success with multiple Tangs in an aquarium. After all, our goal is not to stuff as many Tangs into am aquarium as we can, but rather, we aim to keep our favorites happy and thriving, and successfully for many years to come. Below is a chart comparing the top three most common Genus of Tangs, which can help you choose which combinations you might like to try.





Largest members of the Tang family. Requires 200 gallons minimum for most species.

Most common members of the Tang family and the ones you’ll see most in aquarium stores. Requires 75 gallons minimum for most species to be comfortable, but a lot of them get considerably larger. Aim for 150+.

Second most common Genus collected and sold. Most of these stay on the smaller side and are well suited for tanks as small as 40 gallons wide, but not long term. Aim for 75 gallons for long term health and happiness.

High aggression in regards to territorial behavior. Will not tolerate conspecifics added inappropriately (smaller added afterwards, not enough space, etc.)

Medium aggressive. Mostly focuses territorial behavior on conspecifics, but being highly intelligent creatures, some have more assertive personalities while others have more docile personalities.

Medium aggression in regards to territorial behavior. Generally hates conspecifics and leaves everyone else alone.

Prefers detrivorus and leafly algaes.

Prefers hairy and leafy algaes.

Prefers filamentaceous and leafy algaes.


*Paraacanthurus, aka the Pacific Blue Tang, or Hippo Tang, has largely the same characteristics as Acanthurus. They also grow equally large.


In conclusion…

Tangs have largely the same requirements. Quite simply, the biggest difference is their maximum size, and of course, growth rate. The easiest way to keep more than one in a tank is to add them at the same time, and it helps to choose only one from each of the three Genus. Remember, Tangs need a lot of space to feel comfortable, happy, and healthy. The more you can provide them, the happier they will be. They also like to have friends with them. Because it’s not always easy to upgrade an aquarium, you’ll want to ensure you are choosing your fish appropriately and doing so will ensure years of happiness, good health, and entertainment. That’s where we come in. Your family at Blue Fish aquarium will help you with the entire process, from choosing the least aggressive specimens, to helping you plan when to add them. We are here for you, every step of the way.

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