Xenia makes up a very large and diverse group of octocoral. It is a fleshy, slimy and stalky form of coral that may contain small, oval sclerites or none at all. The corals ability to reproduce rather quickly and its ease of keeping and purchasing it at your local pet shop adds to its noteworthyness.
Most Xenia species are shaped like a stalk of broccoli, which differs from its cousin, Anthelia which tends to grow from an encrusting base. Though Anthelia is often easier to keep and is more hardy than Xenia, this shouldn’t deter you from obtaining this beautiful type of octocoral. Stalks of xenia are usually translucent or white in color with green to a cream colored polyp. Their polyps are non-retractile, that form a distinct capitulum with tentacles that are pinnate(feathery in appearance). Those species that are from deeper water in nature usually will have smaller, thinner tentacles and long anthococodiae, whereas xenia residing in shallow regions with a high light irradiance will have larger and more robust features opposite that of its deeper water counterparts.
The ability for xenia to reproduce so easily and quickly makes them a nice addition to a reef tank. Xenia are usually the first colonizers of a reef tank. Reproducing asexually, mainly through colony fission, they are also able to “walk” from one area to another, while leaving a small part of its original tissue behind to start a new daughter coral, as is also evident in corallimorpharians. Xenia is hermaphroditic and reach sexual maturity by the age of two. The preferred place for xenia to grow is on a vertical surface such as a rock outcropping or wall or even the side of a tank glass.
This ability for xenia to spread prolifically, literally from one side of your tank to the other in as little as a few months, does not come without its pittfalls. Xenia can wreck havoc on stony corals either by direct contact or by inhibitting the amount of available light that the stony coral receives. Some forms of xenia contain terpenoid defense mechanisms to help prevent predatory conflicts, but these chemical substances can affect stony corals as well, though they do not contain nematocysts. Capable of detaching itself from its original place of colonization, xenia can drift and reattach itself in another place which can also prove problematic to neighboring corals if the new inhabitant comes to close to other coral colonies.
Good water circulation and intense lighting are crucial to the overall and long term success of xenia. Believe it or not, xenia like many other filter feeders such as Tridacna Clams feed on nutrients like dissolved organic within the pelagic area of your tank, therefore it is condusive to have less than pristine water where a large population of stonies is not recommended. A dosing of lugol’s iodine or similar iodine supplement is helpful to ensure that your octocorals remain healthy and live a long life. Xenia also has a high rate of turnover of its zooxanthellae used for photosynthesis, which is also used for supplementary nutrition.
Certain species or even the same related daughter colony of xenia will pulsate whereas the colony next to it shows no pulsating at all, has lead to a longstanding debate as their is no conclusive evidence or clear cut reason as to why. It seems that new additions and captive bred species of xenia tend to pulse more so than a mature or wild harvested population of xenia. Certain species of coral such as Sarcophyton along with temperature, chemicals(such as methanol), hormones and water flow are some of the residing factors that can lead to your corals ability to pulse or not.
Predators such as some crabs, nudibranches(looks just like a xenia anthocodia), damsel fish and polychaete worms can pose a problem to xenia and will consume it like a lawnmower cutting your grass. Xenia can crash or “melt” just as quick as it grew in your tank. Shipping of xenia is even more dramatic and comes with a smaller percentage of xenia making it through the collection and shipping process. Temperature and water quality issues are associated with this dilemna.
Overall, xenia is a pretty easy soft coral to keep and it can also be propogated with little effort. Once you get past the initial shipping and placing in your tank, xenia requires nothing more than the basics in terms of it growing and being happy within the confines of your reef tank. remember that placement in relation to other neighboring corals, water flow and optimal lighting will enable you to be successful with this octocoral or possibly lead to its demise or possibly that of neighboring corals that venture to close to it.
