Pulsing xenia care

Quick reference

What is pulsing xenia?

Xenia are soft corals of the family Xeniidae with polyps on fleshy stalks; their relative Anthelia grows from an encrusting mat and mostly doesn't pulse.^[2] The pulsing puzzled naturalists for two centuries. In 2013, Kremien and colleagues showed in the Red Sea xeniid Heteroxenia fuscescens that pulsing pushes water up and away from the colony, stirs the boundary layer around the tissue and lowers the oxygen inside it, which reduces photorespiration; net photosynthesis while pulsing was up to ten times higher than at rest.^[1] The authors argue that this pays for the energy the motion costs.^[1]

Lighting for pulsing xenia

Low to moderate according to Top Shelf Aquatics.^[3] TFH's author saw far more reproduction under metal halide than under fluorescent lighting alone, and noticed pulsing slow when lamps ran past their useful life.^[2] We found no measured PAR range.

Flow and placement

Gentle and indirect. TFH says pulse corals are delicate and won't tolerate a powerhead pointed straight at them, and suggests crossing two flows instead; Top Shelf warns against a jet that pins the polyps down.^{[2, 3]}

Feeding

No target feeding. TFH says xenia live on their zooxanthellae and on dissolved organic compounds rather than captured plankton,^[2] and Top Shelf lists dissolved nutrients and fine particulate food.^[3] Both suggest they do better with some nutrients in the water: TFH notes reefers who export nutrients very aggressively report limited success, and Top Shelf says stability matters more than chasing very low nutrients.^{[2, 3]}

Aggression and spacing

It doesn't sting much, but it competes by growing. TFH says colonies reproduce prolifically, overgrow other species and even climb the glass, spreading by tissue left behind, drifting fragments, dropped branches and free-swimming larvae.^[2] Top Shelf calls it semi-aggressive and says to prune it before it reaches slower-growing neighbours.^[3]

Tankmates

Keep it away from slow-growing corals, and don't place it on rock that connects to the main reef.^[3]

Disease and quarantine

Pulsing can slow or stop for no obvious reason and resume later, which TFH says doesn't necessarily mean anything is wrong.^[2] Colonies can also crash, the tissue falling apart within days; TFH's author lists possibilities from an unidentified nutrient running out to a naturally short lifespan, and says to do water changes, siphon out the dead tissue and correct parameters, because small healthy pieces often regrow.^[2] He hadn't dosed iodine in nearly a decade and his xenia still pulsed and multiplied, so he disputes the common claim that iodine is required.^[2]

Fragging and propagation

Easy to the point of nuisance. TFH suggests gently dislodging pieces and holding them on small rocks with snug rubber bands underwater until they attach in a few days, or wrapping them in bridal veil; unwanted growth on glass can be scraped off with a razor blade.^[2] Handle gently: xenia slime readily and ship poorly, which is why stores often buy it from hobbyists.^[2]

Troubleshooting

Common mistakes

• •Placing it on the main rockwork.^[3]
• •Pointing a powerhead at it.^[2]
• •Stripping nutrients to near zero.^{[2, 3]}
• •Dosing iodine because it stopped pulsing.^[2]

Equipment & food for this species

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Soft corals don't strictly need feeding. Reef Roids help if you want faster growth.

Pulsing xenia FAQ

Why does xenia pulse?

To photosynthesize better: a 2013 PNAS study found pulsing flushes oxygen from the tissue, raising net photosynthesis up to tenfold.^[1]

Why did my xenia stop pulsing?

Often for no clear reason, and it usually resumes; TFH's author linked slowdowns to old lamps.^[2]

Does xenia need iodine?

TFH's author hadn't dosed iodine in almost a decade and his xenia still pulsed and multiplied; we found no study showing it's needed.^[2]

Is xenia invasive?

It can be: it overgrows other corals and climbs glass, so keep it on an isolated rock.^{[2, 3]}

How do you frag xenia?

Dislodge a piece and band it to a small rock until it attaches in a few days.^[2]

What light does xenia need?

Low to moderate according to Top Shelf; TFH's author saw more growth under metal halide.^{[3, 2]}