LPS coral recession usually starts with stress. The tissue pulls away from the skeleton. The exposed skeleton then invites algae, infection, and more decline. Most cases trace back to unstable alkalinity, poor placement, excessive flow, light shock, pests, or hidden aggression. The good news is that many receding LPS corals can recover if you correct the cause quickly and stabilize conditions.

Large polyp stony corals are often sold as hardy beginner corals. That is partly true. Many LPS species tolerate small mistakes better than delicate SPS. Still, they react clearly when something is off. Recession is one of the most common warning signs. It can affect acans, euphyllia, favia, scolymia, blastomussa, trachyphyllia, and many others. In this guide, you will learn why LPS corals recede, how to diagnose the real cause, and what steps can stop the damage. You will also learn how to adjust light, flow, chemistry, feeding, and placement so the coral can rebuild tissue and regain color.

Quick Reference Table

Issue	Common Signs	Likely Cause	First Fix
Tissue pulling from skeleton	White edges, shrinking flesh	Alk swings, stress, infection	Test parameters and stabilize
One side receding	Damage on exposed side	Too much flow or coral warfare	Move coral and inspect neighbors
Sudden decline after new light	Bleaching, tight tissue, recession	Light shock	Reduce intensity and acclimate slowly
Brown jelly or slime	Rapid tissue loss, foul film	Bacterial infection	Isolate, siphon, dip, increase export
Poor inflation and slow recession	Deflated polyps, weak feeding response	Low nutrients or instability	Feed lightly and keep nutrients measurable

What LPS Recession Looks Like

Recession means living tissue is retreating from the coral skeleton. You may first notice a thin white line along the base. In fleshy corals, the polyp may stop inflating fully. In encrusting LPS, the tissue edge may peel back. Some corals recede slowly over weeks. Others crash in a few days. The pattern matters. Recession from the bottom often points to detritus, low flow, or damaged tissue. Recession on one side often suggests direct flow, stings, or shading. Recession from the mouth outward can signal severe stress or infection.

Do not confuse recession with normal daytime contraction. Many LPS corals shrink a bit under strong light. They usually expand again later. True recession exposes bare skeleton. That area will not puff back up. Algae often colonizes it within days. Once algae settles on exposed skeleton, recovery becomes harder. That is why early action matters. If you catch recession before algae and infection spread, the coral has a much better chance.

The Most Common Causes of LPS Recession

Unstable alkalinity is the top cause in many reef tanks. LPS corals can handle a wide range. They do not handle rapid swings well. A jump from 7.2 to 9.0 dKH can trigger recession fast. Calcium and magnesium matter too, but alkalinity changes usually hit first. Salinity swings are another major problem. A faulty ATO, missed top-off, or bad refractometer can stress fleshy corals badly. Temperature spikes also cause fast decline, especially above 82°F.

Placement issues are also common. Too much direct flow tears tissue against sharp skeleton. Too little flow lets waste settle and irritate the coral. Excess light can bleach tissue and weaken it. Sudden light upgrades are especially risky. Chemical warfare is another hidden cause. Favias, chalices, euphyllia, and galaxea can sting nearby corals at night. Fish and invertebrates may also pick at damaged tissue. Finally, pests and infections can turn mild stress into rapid tissue loss. Brown jelly disease is the classic example. It spreads fast and needs immediate action.

Natural Habitat and Why It Matters

Many popular LPS corals come from reef slopes, lagoons, and protected rubble zones. These areas often have moderate light and varied flow. They are not blasted by constant, narrow pump streams. Acans and blastos often live in lower light zones. Euphyllia usually enjoy indirect, moving flow. Trachyphyllia and scolymia often rest on sandy bottoms. Favia and some brains tolerate stronger light, but still prefer stable conditions.

Knowing the natural habitat helps you avoid poor placement. A fleshy open brain placed high under intense LEDs may recede. A torch coral placed in a dead spot may collect waste and decline. LPS corals use tissue expansion to capture food and light. That tissue is soft and vulnerable. In nature, water movement shifts constantly. In aquariums, pumps can create harsh, fixed streams. Matching the coral’s natural environment reduces stress and lowers the chance of recession.

Aquarium Setup for Healthy LPS Corals

Stable systems grow healthy LPS. Tank size matters less than consistency, but larger tanks are more forgiving. A mature 40-gallon breeder often keeps LPS better than a brand-new nano. Use quality rockwork with shelves, shaded areas, and open sand. This gives you placement options. Keep enough space between corals. Many LPS look peaceful by day. At night, sweeper tentacles can reach several inches.

Mechanical filtration helps remove detritus before it settles on coral tissue. A protein skimmer improves oxygen and waste export. Good top-off control prevents salinity swings. Test kits should be accurate and recent. Calibrate your refractometer often. Aim for salinity near 1.025 to 1.026, temperature 77 to 79°F, alkalinity 8 to 9 dKH, calcium 400 to 450 ppm, and magnesium 1250 to 1400 ppm. Nitrate and phosphate should be present, not zero. Many LPS struggle in ultra-low nutrient tanks. A practical range is 5 to 15 ppm nitrate and 0.03 to 0.1 ppm phosphate.

Lighting Requirements

Most LPS corals prefer moderate light. Many thrive around 50 to 150 PAR. Some favia, hammers, and candy canes can handle more. Others, like blastomussa and trachyphyllia, often prefer less. The exact number matters less than consistency and acclimation. Recession often starts after a new fixture, lens change, or schedule increase. Corals that looked fine under old bulbs may bleach under stronger LEDs.

If recession starts after a lighting change, reduce intensity first. Shorten the peak period. Raise the fixture if needed. Use a screen or acclimation mode. Watch for signs of improvement over one to two weeks. Better inflation is a good sign. Do not move the coral repeatedly. Constant relocation adds stress. If you do move it, choose a lower light area with similar flow. For more on balancing intensity and placement, see reef tank lighting guide.

Water Flow

Flow should be indirect, broad, and variable. This is one of the most overlooked factors. Strong direct flow can strip tissue from sharp septa. The coral may look irritated all day. Polyps stay tight. Flesh leans hard in one direction. Over time, the side facing the pump recedes. On the other hand, weak flow traps detritus and bacteria around the coral. That can irritate the base and fuel infection.

Watch how the tissue moves. Healthy movement looks gentle and random. It should not whip or collapse. If food and debris settle on the coral, increase surrounding flow slightly. If flesh is pushed hard against skeleton ridges, reduce direct flow. Euphyllia need visible sway, but not violent motion. Acans and scolys prefer softer movement. If one side is receding, rotate the coral or redirect the pump. For broad flow planning, read reef tank flow guide.

Feeding and Nutrition

LPS corals benefit from regular feeding, especially during recovery. They do not need heavy feeding every day. They do need enough energy to rebuild tissue. Offer small meaty foods two or three times weekly. Good choices include mysis, finely chopped seafood, reef roids, and coral-specific blends. Feed after lights dim if the coral extends feeder tentacles at night.

Do not overfeed a stressed coral. Large chunks can rot on damaged tissue. Start with tiny portions. Turn off pumps briefly so the coral can hold the food. If the coral spits food out, wait a few days and try again. Also remember that fish waste and dissolved nutrients support coral health. Many receding LPS corals improve when tanks move away from sterile conditions. If nutrients are unreadable, feed fish more consistently and reduce aggressive export. Learn more in how to feed corals.

Compatibility and Hidden Aggression

LPS corals often lose tissue because something nearby is attacking them. The aggressor may not be obvious during the day. Sweepers emerge after lights out. Favias, galaxea, and some euphyllia are notorious. A coral can look fine in the morning but get stung nightly. Fish can also cause trouble. Angelfish, some butterflies, and even curious clownfish may nip fleshy corals. Peppermint shrimp and crabs sometimes pick at damaged tissue.

Give each LPS coral enough room. On mixed reefs, leave more space than you think you need. Check the tank an hour after lights out with a flashlight. Look for sweepers and contact points. If recession is limited to the side facing another coral, move one of them. If fish are pecking, isolate the coral with a cage or move the fish. For mixed reef planning, see best LPS corals for beginners and reef safe fish guide.

Step-by-Step: How to Fix a Receding LPS Coral

1. Test alkalinity, salinity, temperature, nitrate, phosphate, calcium, and magnesium. Look for swings, not just bad numbers.
2. Inspect the coral closely. Check for brown jelly, pests, algae on exposed skeleton, and sting marks.
3. Review recent changes. New lights, dosing changes, new pumps, and missed top-off events often explain the problem.
4. Move the coral only if placement is clearly wrong. Choose moderate light and indirect flow.
5. Stabilize alkalinity. Correct slowly. Avoid large one-day adjustments.
6. Keep nutrients measurable. Do not chase zero nitrate or zero phosphate.
7. Feed lightly two or three times each week if the coral accepts food.
8. If infection is present, isolate the coral. Siphon off jelly or slime. Consider an iodine or coral dip based on the species and product directions.
9. Remove algae from exposed skeleton carefully if it spreads onto living tissue.
10. Observe daily for one to two weeks. Improvement often starts with better inflation and no new tissue loss.

Propagation and Fragging

Should You Frag a Receding LPS Coral?

Sometimes fragging saves the healthy part. Sometimes it adds stress and makes things worse. Branching corals, like candy canes and some euphyllia, are the best candidates. If one head is infected or melting, you can often cut away healthy heads. Massive fleshy corals are harder. Acan lords can sometimes be cut between mouths. Trachyphyllia and scolymia are poor emergency frag candidates for most hobbyists.

Best Practices for Fragging

Use clean tools. Cut only through clear skeletal separation when possible. Avoid slicing through inflated tissue. Dip the frag if appropriate. Then place it in moderate flow and lower light. Fragging works best when recession is localized and the remaining tissue looks strong. If the whole coral is weak, focus on stability first.

Common Problems

Why Is My LPS Coral Receding From the Base?

Base recession often points to detritus buildup, low flow, or chronic irritation. It can also happen when a coral sits on sharp rock or unstable rubble. Check for debris trapped under the tissue. Lift the coral gently and inspect the underside. Improve surrounding flow without blasting the coral. Keep the base clean and free of algae.

Why Is Only One Side Receding?

One-sided recession usually means directional stress. The common causes are direct flow, stings, shading, or fish picking. Follow the line of damage. See what sits nearest that side. Redirect pumps and increase spacing. Nighttime inspection often reveals the answer.

Can a Receding LPS Coral Recover?

Yes, many can recover if tissue loss stops early. Recovery is slow. The coral first needs stable inflation and feeding response. Then tissue begins to creep back over clean skeleton. Heavily algae-covered areas may never regrow fully. Still, many corals survive and regain size over months.

What If Brown Jelly Appears?

Act fast. Remove the coral if possible. Siphon away the jelly outside the display. Dip the coral using a reef-safe product and label directions. Increase export and check nearby corals. Brown jelly can spread quickly, especially among euphyllia and damaged fleshy LPS.

Frequently Asked Questions

How long does LPS coral recovery take?

Visible improvement may start within one to two weeks. Full regrowth often takes months. Stability matters more than quick fixes.

Should I dip every receding LPS coral?

No. Dip when you suspect infection, pests, or recent introduction stress. If the cause is flow or chemistry, a dip alone will not solve it.

Is low nitrate bad for LPS corals?

It can be. Many LPS corals struggle in tanks with unreadable nitrate and phosphate. Aim for stable, measurable nutrients.

Can too much alkalinity cause recession?

Yes, especially if alkalinity rises quickly. High alkalinity with very low nutrients can also stress LPS corals.

Should I move a receding coral to quarantine?

Move it if infection is likely or if tankmates are bothering it. Otherwise, avoid unnecessary moves and fix the root issue in place.

LPS recession is frustrating, but it is rarely random. The coral is reacting to stress you can usually identify. Start with stability. Check alkalinity, salinity, temperature, nutrients, light, and flow. Then look for aggression, pests, and infection. Make calm, targeted changes. Avoid chasing numbers daily. When the environment improves, many LPS corals respond with better inflation, stronger feeding, and slow tissue regrowth. In reef keeping, consistency saves more corals than dramatic intervention.