Xenia and Kenya Tree Care: Pulsing, Spreading and Placement

Buy one xenia frag and a year later you have one of two tanks. In the first, a rock covered in pulsing hands that everyone who walks by stops to watch. In the second, you are peeling xenia off the base of your stony corals with tweezers every Sunday. It is the same coral. The difference is where you put it. Kenya tree works the same way, just slower: it drops branches that tumble off and root wherever they land.

Xenia and Kenya tree get bought together for the same reasons. Both are soft corals with no stony skeleton, both are easy to keep alive, and both grow fast. That last part is the gift and the problem. In the right tank they fill bare rock and give you frags to trade. In the wrong tank they climb over slower corals. This guide covers both, side by side, and is honest about where each one belongs.

Quick facts

	Pulsing xenia	Kenya tree
Genus and family	Xenia sp., family Xeniidae	Capnella sp., family Nephtheidae
Looks like	Soft stalks topped with feathery polyps that pump open and closed	A small tree: a soft trunk splitting into branches tipped with fuzzy polyps
Light	Low to medium. Our listings give PAR 75 to 150.	Low to medium. Our listings give PAR 75 to 150. Adapts to more.
Flow	Low to medium, indirect	Moderate and changing, never a direct jet
Placement	Its own rock or an island, lower to middle rockwork	Lower to middle rockwork, with room to grow up and out
How it spreads	Creeps across rock and drops new stalks	Drops branches that roll off and root nearby
Feeding	None needed	None needed
Main risk	Overgrows slower corals	Chemicals that bother stony corals in small tanks

Why xenia pulses

For about 200 years nobody knew. In 2013 a team from the Hebrew University of Jerusalem and the Technion published the answer in the Proceedings of the National Academy of Sciences. They studied a pulsing relative of xenia, Heteroxenia fuscescens, on the reef at Eilat in the Red Sea.

Corals make oxygen when their algae photosynthesize, and too much oxygen sitting against the tissue slows photosynthesis down. Each pulse pushes that oxygen-rich water away and pulls fresh water in. Colonies that were pulsing photosynthesized at roughly ten times the rate of colonies that were not. When the researchers raised the oxygen in the water around the coral, the boost disappeared, which is how they knew oxygen was the reason. Pulsing costs the coral energy, but the gain in food from its algae is worth more.

That has a practical side. Xenia pulses to feed itself from light, so strong pulsing usually means it is getting what it needs. When it slows or stops, something in the light, flow or water has changed. Our zooxanthellae guide explains the algae doing the work inside the tissue.

Light

Our listings give both corals PAR 75 to 150. Published ranges for xenia run a little wider, up to about 200, and growers agree it does best in the low to middle of that range. Too little light slows its growth and its pulsing.

Kenya tree is even more forgiving. Growers report it doing fine anywhere from low light to strong light once it has adjusted, which is one reason it is sold as a first coral. As with any coral, start a new piece low and move it up only after it has settled.

Flow and placement

Give xenia gentle, indirect flow. This is the setting people get wrong most often. A powerhead pointed at it keeps the polyps pinned down and closed, and a colony that cannot open cannot pulse. You want the stalks swaying a little and the polyps free to open all the way. Too little flow lets detritus settle on it, so do not tuck it into a dead corner either.

Kenya tree wants moderate, changing flow that keeps the branches moving. That movement also helps it shed the thin waxy film it puts out every so often. A direct jet from close range can damage the tissue and make it pull in.

Placement is where you decide whether these corals are a gift or a weed. Put xenia on its own rock, ideally with sand all the way around it, so it has nowhere to creep. A rock island in the middle of the sand bed is the classic setup. Kenya tree can go on the main rockwork, lower to middle, but give it space above and to the sides, because it grows up and out, and downstream of corals that are sensitive to soft-coral chemicals.

How they spread, and where that is a problem

Xenia spreads two ways. The colony creeps across rock, and it puts up new stalks around the edge. Small pieces also break off, drift and attach somewhere else. Left alone on connected rockwork, it can reach every rock in the tank.

Kenya tree spreads by dropping branches. A branch swells, lets go, rolls around in the current and attaches wherever it settles. That is normal reproduction, not a sign of trouble. It is easier to control than xenia, because you can pick up the fallen branches before they root.

Where they are a gift	Where they become a weed
A new tank with bare rock and nothing slow-growing yet	A stony coral tank, where they grow over corals that cannot fight back
A tank of other tough, fast-growing soft corals	Connected rockwork with no gaps, where xenia can walk anywhere
A rock island surrounded by sand	Small tanks crowded with slow corals such as chalices and favias
A frag tank, if you want frags to trade or give away	Any tank where you are not willing to prune every few weeks

If you already have xenia somewhere you do not want it, peel the stalks off at the base rather than cutting them partway down. Siphon the loose pieces out so they do not resettle.

Kenya tree and stony corals

Kenya tree is peaceful in the sense that it does not sting. Like the leathers it is sold with, it can release chemicals into the water that bother stony corals, especially in a small tank. Sources disagree on how much this matters. Some rate it aggressive for that reason, and others say it is rarely a problem for hard corals. The safe approach costs little: run activated carbon, keep up with water changes, and do not set it right next to your stony corals or upstream of them.

Kenya tree is sold as a leather coral, but it is in a different family, Nephtheidae, from the classic leathers. Our classic soft corals page covers the leathers, clove polyps and pipe organ if you are building a soft coral tank.

Water and nutrients

Neither coral needs target feeding. Both get most of what they need from light and from what is already in the water. Our listings call for salinity 1.025 to 1.026, temperature 76 to 78°F, alkalinity 8 to 9 dKH, calcium 420 to 440 ppm and magnesium 1300 to 1400 ppm.

The bigger issue is nutrients. Xenia does best with some nitrate and phosphate in the water. In tanks run close to zero, it pulses less and grows less. Kenya tree tolerates a richer tank than most corals. Steady salinity, temperature and alkalinity matter more for both than chasing low numbers.

Why xenia stops pulsing

What you see	Likely cause	What to do
Polyps closed or flattened, colony pushed to one side	Flow too strong or too direct	Turn the pump away or move the rock. Indirect flow only.
Pulsing slowed after a big cleanup or new phosphate media	Nutrients dropped near zero	Let nitrate and phosphate come back up to measurable levels
Slow pulsing and slow growth	Not enough light	Move it up a little at a time
Whole colony shrinks or melts in a day or two	A sudden swing in salinity or temperature, often from a missed top-off	Check salinity and the heater, fix the swing, and do a water change
A new frag that will not pulse	Still adjusting to your tank	Give it a week or two of stable water before moving it

Our listing puts it simply: a colony that stops pulsing is usually telling you something changed in the water. Check what changed in the last few days before you move the coral.

Why Kenya tree looks droopy

Every so often a Kenya tree shrinks down, closes up and looks half dead. Usually it is shedding. It puts out a thin waxy film to clear off debris and algae, then opens back up once the film washes away, typically within a day or two. Flow helps it shed. If it stays shrunk for much longer than that, check your water and look at what it is touching or sitting downstream of.

Fragging

Both are about as easy as fragging gets, which is why they are such common trade frags.

• Xenia: let a stalk get big, then peel it off the rock at the base, or slice it with a clean blade. Hold it against a frag plug or a piece of rubble with a rubber band that is snug but not tight. Once it has attached, take the band off.
• Kenya tree: cut a branch with sharp scissors, then band it to a plug the same way. The base cements itself down as it heals. You can also just collect the branches it drops on its own.

Acclimation and dipping

Corals do not need a drip. Turn the tank lights off and float the sealed bag for 15 minutes to match temperature. Open it into a clean container and add small amounts of tank water every few minutes for 15 to 30 minutes. Dip the coral in a coral dip, following the label, then rinse it in clean tank water. Throw the bag water away. Place it low, with the light off or dim for the first day. Our acclimation and dipping guide has the details, and our coral dips are in the store.

FAQ

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