Looking to get into keeping corals, but worried your tank is too low-tech to sustain these often picky and unforgiving organisms? Or maybe you just don’t want to spend too much time doing underwater gardening? We’ve got just the thing for you: pulsing Xenia, one of the easiest corals to grow in a saltwater aquarium.
Below, find everything you need to know about pulsing Xenia, including how to recognize it, what it needs to grow, and how to frag it. But be warned, as this coral is so proliferous that some aquarists avoid it due to worries of it overtaking their tanks!
| Name (Common, Scientific) | Pulsing Xenia, pulsing xenid, Unomia stolonifera, Heteroxenia fuscescens |
| Temperature | 74-80 °F |
| Salinity | 1.023-1.025 |
| pH | 8.1-8.4 |
| Difficulty level | Easy |
| dkH | 8-11 |
Pulsing Xenia characteristics & natural habitat
Taxonomy
The common name “pulsing Xenia” is often broadly used for different species in a large family of corals known as the Xeniidae. Two of these are very common in the aquarium hobby: Unomia stolonifera and Heteroxenia fuscescens.
The latter used to be scientifically known as Xenia elongata, but its name was changed in 2021 based on new research. This is not unusual: the Xeniidae are notoriously difficult to classify, and their Latin names are always changing. The genus Unomia was coined especially for this coral, plus one other closely related species.
Appearance
Pulsing Xenia is definitely one of the more visually interesting corals you can keep. As the common name suggests, its most fascinating characteristic is the fact that it moves. Yes, all corals move to some degree—but Xenias do so much more quickly and frequently.
This is a soft coral that forms part of the class of corals and other marine invertebrates known as Octocorallia, which can be recognized by their star-shaped polyps that display 8-fold symmetry.
On this species, these feathery polyps are constantly opening and closing, which in 2013 was discovered to help their zooxanthellae (photosynthesizing unicellular organisms that live in their tissues) do their job of synthesizing light into nutrients. Additionally, it ensures the water around the polyps stays nice and fresh.
Xenias are appreciated for their elegant looks. They grow on fleshy, mostly bare stalks, with the pulsing polyps—reminiscent of palm trees—gently waving in the flow. Depending on the species and variety, they can be pinkish-purple, cream, or tan to brown in color.
Natural habitat
The two pulsing Xenia species commonly kept in the aquarium are mostly found in shallow coral reefs. They’re native to the tropical Indo-Pacific, where they’re quite successful thanks to their adaptable nature and ability to take hold on almost any type of substrate.
Unfortunately, as a result of human activity, this flexibility in terms of habitat has allowedXenias to spread beyond their natural range. Unomia stolonifera in particular is incredibly invasive and has already managed to establish itself in the Caribbean, particularly in Venezuela, and completely take over entire reefs.
Pulsing Xenia care
Do you really want pulsing Xenia?
Before we go into pulsing Xenia care, we’d like to take a moment to ask you if you’re sure about this. As we mentioned briefly in the intro, this coral is very prolific. It’s easy to grow and spreads quickly—much too quickly, for some. And once it’s in your tank, there are no take backsies, as it can regrow from even the tiniest piece drifting around the water column.
If you’ve got a nice reef tank with different corals, we strongly urge you to think twice about adding pulsing Xenia. Unless you’re willing to do near constant pruning, there’s a good chance it’ll choke out your other corals.
On the other hand, if you just want to add some easy coral life to an otherwise coral-less aquarium, or if you’re setting up a super low-tech tank, the Xeniidae can make a good choice for you. They really are very nice to look at, after all!
Compatibility
As mentioned, pulsing Xenia doesn’t play nice with the neighbors. All corals have stinging cells called cnidocytes, which some species use to wage vicious wars on their neighbors. Xenia doesn’t attack—it’s quite peaceful in that sense—but it still tends to end up overtaking other corals and anemones by simply outgrowing them and outcompeting them for nutrients.
Some sources recommend placing aggressive corals like torches around pulsing Xenia so they can help keep it under control with their cnidocytes, but there’s no 100% guarantee this will work. As such, we think Xenia is best for a single-coral tank.
As for fish, pulsing Xenia does actually make a good choice to keep with species listed as “mostly reef safe” or “tentatively reef safe”, like dwarf angelfish. These may nip at corals, but Xenias are unlikely to care much. They usually grow back quickly enough to survive just fine.
Placement
Soft corals like this one like plenty of light, and a pulsing Xenia will grow the fastest in a spot with medium to high light levels. Their zooxanthellae can’t photosynthesize as well in a shaded location. In fact, if you’re one of the many aquarists having trouble with a Xenia gone wild, placing it in a low-medium light location instead may help curb its growth.
Pulsing Xenia doesn’t mind some flow, but do keep in mind that the flow level will affect how well you can see the fascinating pulsating movements of the polyps. We think this coral looks its best in a low to medium flow location in the tank.
All in all, the lower to middle layer of the tank should work well.
Maintenance
Pulsing Xenia is great for low-tech tanks, but it does need regular attention to keep it from totally overgrowing everything. To prune your Xenia, use large tweezers or forceps to grab the base and then twist and pull to pop it off the rock it’s growing on.
We recommend turning the flow off while pruning and trying to prevent any bits of Xenia from floating away. Small pieces can regrow wherever they land, and assuming you’re pruning in an attempt to control your coral, that’s obviously not ideal.
Since this coral can absorb nutrients directly from the water (see below), staying on top of water changes can help curb excessive growth.
Feeding
One of the factors that makes pulsing Xenia so easy to grow is the fact that it usually doesn’t need to be fed. Xeniidae have zooxanthellae, which create nutrients for them through photosynthesis, and they also have the ability to catch small particles with their polyps. In addition, they can absorb dissolved nutrients directly from the water.
Testing your water parameters can help you figure out whether you should be feeding your pulsing Xenia. If the phosphate level is between 0.03-0.1 ppm and the nitrate between 5-20 ppm, there’s usually no need.
If the nutrient levels are very low, it could be helpful to target feed your Xenia with bioplankton from time to time, like once a week or so. Don’t feed if you’re already having problems with the coral overgrowing your tank!
Fragging pulsing Xenia
There really isn’t much to say here. As we’ve mentioned, Xenia is almost impossible to get rid of once it’s in your tank. Even tiny pieces can regrow, and “accidental fragging” is very common.
If you want to multiply your pulsing Xenia for some reason, you can really do so any way you want. Cut, slice, tear, or snip pieces off the main coral and attach them to some rock with a rubber band. Or just throw them in a sump with some rock rubble—they’ll attach themselves, no help from you required.
FAQ
Although it’s basically an underwater weed, some folks can’t get pulsing Xenia to thrive in their tanks. It just melts away! In some cases, this is due to a lack of nutrients such as nitrates. It can sometimes be challenging to keep your tank clean, but not so clean that your Xenia starves. Supplemental feedings could help.
Did you do a water test? Could the flow be too strong? Or maybe the temperature is too high, which can also make the polyps stop moving. And remember, if your Xenia is healthy, not seeing much movement isn’t too alarming.
Conclusion
Pulsing Xenia lends its name from the unique pulsing movements of its polyps. This is one of the easiest and fastest-growing corals to keep in a marine aquarium. In fact, it’s so vigorous you may want to avoid it unless you’re setting up a single-coral tank!
If you’d like a beautiful reef tank full of pulsing Xenia or other colorful corals but feel you lack the time or expertise, we can help. Whether you want a nano home reef or a huge office tank, contact us and the FantaSEA team will help make all your aquarium dreams come true.
PS: Looking for more super-easy corals that grow like weeds? Try the green star polyp (GSP), another species that some aquarists prefer to avoid due to its quick growth. In fact, we think GSP may be the only thing that can outcompete pulsing Xenia!
Sources & further reading
Benayahu, Y., OFWEGEN, L. P., Allais, J. P., & Mcfadden, C. S. (2021). Revisiting the type of Cespitularia stolonifera Gohar, 1938 leads to the description of a new genus and a species of the family Xeniidae (Octocorallia, Alcyonacea). Zootaxa, 4964(2).
Kremien, M., Shavit, U., Mass, T., & Genin, A. (2013). Benefit of pulsation in soft corals. Proceedings of the National Academy of Sciences, 110(22), 8978-8983.
Ruiz-Allais, J. P., Benayahu, Y., & Lasso-Alcalá, O. M. (2021). The invasive octocoral Unomia stolonifera (Alcyonacea, Xeniidae) is dominating the benthos in the Southeastern Caribbean Sea. Memoria de la Fundación La Salle de Ciencias Naturales, 79(187).
