Tangs and surgeonfish are a diverse, beautiful, and often highly personable group of fish. It is no wonder that so many of us want to keep these fish in our systems. Inexperienced keepers do the right thing by going to their favorite forums and sites to ask which tangs can be kept, what size tank is appropriate, and how many they can keep in a particular system.
Unfortunately, there has long been disagreement among certain hobbyists on precisely how to answer these questions—with some being much more restrictive than others when it comes to the species, tank sizes, and number of specimens recommended. In some instances, heated arguments occur as a result. Folks on both sides of the issue are generally well-meaning. Certainly neither side wants to bring harm to captive tangs. So why all the fuss then?
An overlooked ailment
I believe a good deal of the original disagreement actually stemmed from problems created by an unrelated group of ailments that few people at the time correctly identified. While I can’t be much help in resolving any lingering disputes, maybe the following information can be of help to some of my new-to-tang-keeping friends out there.
For several years, my high school students and I have been passively involved in stress hormone studies of parrotfish with University of Toledo Medical Center professor Dr. John Turner. He successfully linked empirical data showing that increased stress causes numerous health conditions observed in parrotfish on coral reefs around the Caribbean Sea and the Bahamas island chain. The same sort of research has not been conducted on tangs, so I am making a suppositional leap from parrots to tangs, but I firmly believe the two groups of species respond in similar ways to increased hormone production induced by stress.
The effects of chronic stress
What does stress have to do with housing tangs in captivity? Everything. Any tang will live in a small tank, at least for a time. But as each day passes, the odds of the fish’s demise increase. Why? Chronic stress! Fish rarely die of stress. Rather, they succumb to the effects stress has on their bodies.
Increased stress experienced over a long period causes numerous negative effects. Dr. Turner found that in areas where the parrotfish experienced regular elevated levels of stress (in other words chronic stress) parrots were fewer in number, lower in reproduction rates, smaller in size, and far more likely to exhibit symptoms of various disorders and diseases. In short, chronic stress is killing off whole populations of parrotfish.
Each species of tang and surgeonfish has its own niche in the world. Yet each group shares the same basic needs: enough room to roam, a variety of foods, and places to avoid the aggression of others. Some keepers observed that tangs kept in smaller tanks seemed more likely to develop diseases or other health conditions or simply fail to thrive. But because they didn’t identify stress as the root cause, their advice to house tangs in larger tanks was not always well received.
Their critics were not completely off base, as no empirical data exists clearly demonstrating an ideal minimum aquarium size for any species of tang. What is generally clear, however, is that the bigger the tank, the better the tang’s chances of surviving.
How big is big enough?
Recommended tank size is the most common area of disagreement in the tang-keeping debate. After countless requests for specific advice, experienced keepers came up with some arbitrary minimum sizes—typically in the range of 125 to 150 gallons. But then other keepers will claim their tangs are doing great in a 90-gallon or even smaller tank.
However, what we don’t often hear about is long-term success keeping tangs in those small tanks. Far too often we hear tang deaths being attributed to ich, a spike in dissolved nutrients, a fight with a tankmate, a “weird disease,” “just plain bad luck,” or some other unknown cause.
I am asserting that the root cause of most of the above deaths is actually chronic stress. The keeper failed to provide proper space for the species to swim comfortably, enough safe hiding places in order to avoid the occasional aggression that happens even in the most peaceful of tanks, or a balanced diet of the right greens and high-quality meaty foods.
I know what you are thinking: “I don’t have a big tank, so that must mean no tangs for me.” That is not exactly what I am saying. I am saying that you need to meet the requirements of your particular tang. There are a couple of tang species that will do fine even in a tank as small as 90 gallons. For example, both Kole tangs (Ctenochaetus strigosus) and chevrons (Ctenochaetus hawaiiensis) are relatively small as adults and usually adapt to a limited amount of swimming room far better than the tangs that grow to a foot in length or more.
While it is quite possible to keep those species, I am not saying that every 90-gallon system is necessarily right for them either. The keeper must build their system with the tang’s needs in mind. The tang should be the biggest fish in the system. The system must also be free of smaller but harassing fish, such as sixline wrasses (Pseudocheilinus hexataenia), or very territorial fish like some clown species. Rockwork must be arranged to allow the tang to seek shelter whenever it feels the need and to have a safe place to sleep at night. Equally important, the keeper must provide a regularly available source of grazing greens and a daily variety of meaty foods.
Of course, having a large system does not automatically mean you can keep a tang or group of different tang species. Again, long-term success hinges on the keeper meeting that species’ or group of species’ special needs. It is important to remember that the best chance of success in keeping a group of tangs in the same tank is to add the least aggressive fish first and then slowly add the rougher ones later (and smaller if possible). Again, providing hiding places, proper nutrition, and tolerable tankmates are critical in creating a low-stress environment.
Tough questions, elusive answers
There are two more questions related to chronic stress and tangs. The first is, which species are compatible with each other in your aquarium? The second is whether it’s okay to buy a juvenile tang with the intention of either buying a bigger system later or simply passing the fish on to someone with a bigger tank later.
These questions aren’t any easier to answer than our first questions. Species compatibility is tough because fish don’t all respond to the same stimulus in the same way. Two identical tanks stocked with identical species groupings often vary in the level of aggression and other interactions. The bottom line here is that each individual is a risk in terms of how well it will get along and how well it will adapt to a captive environment. Keepers reduce their risk by looking at general trends. If you are reading from multiple sources that a certain two or three tang species are often successfully kept together, the risk of failure will be less than if you are reading the opposite.
As for the second question, I discourage keepers from buying young fish with the intention of trading up to a larger tank or trading the fish away when they get too big for their system. Far too often, fish in these scenarios don’t live long enough to be moved to a larger home. Even the small versions of our favorite fish experience a great deal of stress just as their adult counterparts would and for the exact same reasons.
We can prevent chronic stress!
Chronic stress, brought on by us failing to meet all of a tang’s needs, compromises the fish’s ability to fight off diseases and to thrive in general. Keeping a fish for a few weeks or months is not long enough to claim success. The effects of chronic stress may take months to even a year or more to become fully evident. This fact is not an excuse for poor husbandry.
If you ask me whether you are safe in keeping a certain tang in a specific system, my answer will not be based upon arbitrary tank sizes, but rather on how the entire environment comes together for the tang. After all, I am acting in your best interest as well as my own. Buying a fish that will not live a year in your system is not only a waste of the fish’s life and your money, but it also drives the price up for the next person, as the demand is one fish higher than it should be.
