Fast Pulse Xenia: Xenia elongata

Phylum: Class: Order: Family: Genus: Species:
Cnidaria Anthozoa Alcyonaria Xeniidae Xenia X. elongata

Common Names:  Xenia Elongata, Fast-Pulse Xenia, Xenia is sometimes referred to a Pulse Corals.

Scientific Name:  Xenia elongata

Xenia Elongata has sturdy stalks up to 3″ long which are light to medium tan in color.  The end of the stalk is covered with a crown of feathery polyps, each carried on a stem approximately 1″-2″ long.  The polyps open and close in an attractive pulsing or pumping motion.  Groups of these stalks form colonies that can spread into large mats in the wilds.  Xenia is one of the few corals that actually smells bad when removed from the water.

Natural Environment:

Xenia is an interesting family of coral as far as hardiness is concerned.  Some hobbyist cannot seem to keep this coral alive and others find it to be a fast growing ‘weed’ coral.  Although there are some guidelines which can be followed to improve the chance of success, no one fully understands what will guarantee success with this coral.  Even a colony that has been thriving in a tank for an extended period of time can quickly go into decline and die for no obvious reason.  Xenia Elongata does seem to be one of the more hardy varieties and it is the most likely to become a pest.

Requires moderate to strong lighting.  Usually, brighter is better although some hobbyist appear to have very good success with lower light levels.

Water Current:
Xenia require at least moderate water flow.  They are one of the few corals that seem content to be right against the strong laminar output of a power head.  In still waters the pumping usually diminishes and the coral goes into decline.

Low. Xenia does not possess any apparent stinging capability and will not bother other corals, but can tend to grow over and shadow its neighbors.  When happy, the coral can reproduce by division at an alarming rate and may require frequent pruning to keep it from crowding out other corals.  When pruning or otherwise being manhandled, Xenia tend to secret compounds into the water that can be injurious to the other tank inhabitants.  If pruning, stalks should be removed whole where possible rather than cutting the coral in the aquarium.

Xenia are photosynthetic and does not accept any known foods.  It is thought that they absorb some of their nutrients directly from the water via dissolved organics.  In fact, some hobbyist keep large colonies of Xenia as filter beds where the xenia is regularly pruned for nutrient export.  It is unclear if this is very effective. Xenia may do better in tanks that are not heavily skimmed, but I have seen them grow prolifically in heavily skimmed SPS tanks.

The reason for the pulsing motion of Xenia has long been a mystery and unclear if it was somehow tied to its feeding strategy.  Recent research by the Hebrew University of Jerusalem indicates that the pulsing motion is used to move water through the colony thus increasing oxygen levels as new water is pulled in and improving photosynthesis rates by up to 10x over when they were not pulsing.

Supplements & Water Chemistry:
Salinity should be maintained between sg 1.024 and 1.026.
Alkalinity should be maintained in the dKH 8-12 range.  Below about 8 dKH, the Xenia pulsing may slow or stop completely.
Calcium does not seem critical, but should be maintained at 380 ppm or higher.
pH should be maintained between 8.1-8.4.  There is some evidence that low pH can cause the pulsing to cease.

Iodine supplementation is sometimes associated by some aquarists with successfully keeping Xenia.  I personally have tried both with and without iodine supplements and have noticed no difference.

Does well within a range of at least 74º to 82º F.  In my experience, Xenia tend to be one of the first coral to show signs of heat stress once the temperature starts getting up in the 84+ range.

Tank Positioning:
Usually kept high up on the reef for strong water flow and highest possible lighting.  Xenia will reproduce in the tank by attaching its stalk against adjacent surfaces it contacts and splitting into two colonies.  In this way, Xenia colonies tend to ‘walk’ in the direction that water movement bends their stalks, so you may want to consider this in your placement.  Xenia can usually be coaxed to grow up the back glass of the tank and can form a nice background display which is out of the way of the other coral.

As noted above, Xenia will readily reproduce in the display tank by attaching it’s stalk to a nearby adjacent surface that it can touch and splitting the stalk in two.  Xenia can be scrapped off smooth surfaces  and can be gently pulled up by walking a fingernail around the base of the coral to slowly loosen it on most rough surfaces.  They can be attached to new substrates using a rubber band or similar method to ensure the Xenia stalk stays in contact with the surface until it attaches.  Due to the soft body, you have to be careful of the rubber band slicing through the Xenia, so you don’t want it too tight.

You can also place suitable substrates in its growth path in the display tank to which it can attach and then be removed.

Xenia also has a great ability to regenerate from relatively small pieces

Wild colony by Professor Steve Oakley.  All other photos by ReefCorner © All Rights Reserved