Acanthastrea lordhowensis (Micromussa lordhowensis)

Acanthastrea lordhowensis (Micromussa lordhowensis) — complete profile
Acanthastrea lordhowensis or Micromussa lordhowensis, fleshy-polyp LPS colony in a marine aquarium
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Acanthastrea lordhowensis — Micromussa lordhowensis

📘 Reading time: calculating… 📅 April 2026 🪸 LPS coral, fleshy polyp 🎯 Placement · Tissue reading

There are corals that impress because of their structure. This one impresses because of its tissue, volume, and color. But that is also exactly why it can be deceptive. When a lordhowensis is doing well, it looks easy. When it is poorly placed, decline usually starts quietly: less inflation, less color, a tighter edge, thinner tissue. This profile is designed to read that process before it reaches the skeleton.

📌 The real risk of the Acan Lord
It is not chemistry. It is placement: too much light, uncomfortable flow, and aggressive neighbors are the classic sequence of decline. Everything else is usually a consequence.

Introduction: an LPS that seems forgiving… until it isn’t

Acanthastrea lordhowensis colony in main view
The typical image people fall in love with: inflated tissue, well-defined polyps, and color contrast within the colony.

The so-called «Acan Lord» has earned a reputation as an attractive and relatively grateful coral. That reputation is partly true, but incomplete. It usually does not fail because of a single brutal cause, but because of accumulated micro-mistakes: too much light, uncomfortable flow, chronic hunger, aggressive neighbors, or buying a specimen that is already tired.

The right reading is not «it can take a lot.» The right reading is this: it gives you room for error if the system is coherent.

Core idea: this coral does not ask for exotic numbers. It asks for coherence in energy, flow, space, and feeding.
Experience — A healthy lordhowensis does not look «hard.» It looks alive, inflated, and purposeful in its tissue. If it starts to look «sharper,» something in the system is no longer fitting together.

Identification: what you really need to look at

Macro of an individual Acanthastrea lordhowensis polyp
Polyp macro — central mouth, thick tissue, and fleshy surface.
Top view of an Acanthastrea lordhowensis colony
Top view — clear separation between polyps and expanded tissue covering the skeleton.
Anatomical infographic of the Acanthastrea lordhowensis polyp
Useful anatomy — mouth, tissue, septa, and skeletal base.
FeatureWhat to expectWhy it matters
PolypsLarge, fleshy, round or ovalIf they look flat or tight, suspect stress or incomplete adaptation.
MouthCentral and well definedIt helps you read feeding response and real turgor.
Visible skeletonIt should not dominate the view in a healthy coralWhen it starts to show clearly, the safety margin is shrinking.
ColorStrong contrast but not «impossible neon»Extreme color in a photo does not always equal real health.
Key point: in the trade you will still see a lot of «Acanthastrea lordhowensis«. At the current taxonomic level, the accepted name is Micromussa lordhowensis. In reefkeeping both names still coexist, so in this profile we use the classic hobby name without losing rigor.

Taxonomy: why it is no longer, strictly speaking, an Acanthastrea

For years the hobby grouped this coral under Acanthastrea. The morphological and molecular revision of Lobophylliidae changed that framework: the accepted name today is Micromussa lordhowensis. The change is not a laboratory whim; it affects how we understand its relationships and why some corals that «look similar» in shops are not actually that close.

What is useful for AtlasReef

  • You can title the profile «Acanthastrea lordhowensis» for SEO and hobby recognition.
  • Inside the article, it is worth clarifying that the accepted name is Micromussa lordhowensis.
  • This helps avoid casually mixing it with other commercial «acans.»

What this clarification avoids

  • Confusing old taxonomy with current taxonomy.
  • Assuming that all colorful, fleshy-polyp corals share the same requirements.
  • Buying by store label without looking at the real morphology.

Biotope and natural context

Natural habitat of Acanthastrea lordhowensis
In nature it appears associated with reef and hard substrate, not as a coral exposed to brutally constant SPS-style light.

Its ecological logic fits a thick-polyp coral that combines photosynthesis with food capture when conditions allow. That already gives you a practical clue: it does not need to be treated like an SPS.

When the aquarist subjects it to the idea that «more light = better color,» the classic sequence often begins: forced color, thinner tissue, less inflation, and accumulated stress.

Practical translation: think of an LPS coral that wants energy security, not light punishment.

Recommended setup: the system where it really shines

What suits it well

  • A stable, mature reef without silly swings.
  • A low or lower-middle area of the aquarium as the starting point.
  • Indirect flow, enough to move water but not enough to «whip» the tissue.
  • Space around it: this coral is not as innocent as it looks.

What damages it

  • Moving it too high too soon in search of color.
  • Direct flow that prevents comfortable inflation.
  • Aggressive neighbors at short distance.
  • A newly built setup that still does not «think» like an ecosystem.

This coral improves greatly when the aquarium already has biological maturity, not just chemical numbers.

Placement in the tank: where it starts to work

Infographic on Acanthastrea lordhowensis lighting and flow
The correct visual guide: start low or lower-middle and only move it upward if the coral gives you reasons to.

The method that works best with this coral is boring, and that is why it works: start conservatively. Place it in an area of low to moderate light and gentle flow. Then observe inflation, color, opening, and feeding response.

ScenarioReadingWhat you do
Very inflated, stable colorEnergy intake is working wellKeep the position.
Well inflated but darkNot a problem by itselfDo not move it up out of aesthetic anxiety.
Less inflation and washed-out colorToo much light or flow stressReduce energy / relocate / observe.
Thin tissue and skeleton showingYou are already lateGentle intervention, not abrupt intervention.

Water parameters: practical ranges, no theatrics

ParameterPractical rangeWhat really matters
Temperature24–26 °CStability matters more than chasing a pretty number.
Salinity1.025–1.026Avoid sawtooth swings from top-off or poorly prepared water changes.
pH8.0–8.4Do not turn an LPS coral into a victim of nervous corrections.
Alkalinity7.5–9 dKHMore than the number itself: consistency.
Calcium400–450 mg/LA growth foundation, but not enough by itself to explain tissue health.
Magnesium1250–1400 mg/LSupports the system’s general balance.
NitratesLow to moderateAn LPS does not need «dead» water.
PhosphatesLow but detectableChasing absolute zero usually ends worse.
What works and what doesn’t

✔ Works

  • Stable routine.
  • Reasonable changes.
  • Reading the coral before making impulsive chemical reactions.

✖ Doesn’t work

  • Moving it every three days.
  • Correcting several parameters at once.
  • Confusing «very clean water» with LPS health.

Feeding: yes, photosynthesis, but not only that

Acanthastrea lordhowensis feeding with tentacles extended
Feeding: one of the most useful images for understanding that this coral does not live on light alone.

Like other LPS corals, it combines input from its photosynthetic symbionts with food capture. That does not mean force-feeding it without control. It means understanding that it can benefit from target feeding or water-column feeding if the system handles it well.

  • Small, manageable particles.
  • Best when the coral shows tentacle response.
  • A little, done well, is better than a lot, done dirty.
  • If the tissue is tight or the coral closes up, do not insist.
AtlasReef rule: feed to support tissue and recovery, not to turn the aquarium into soup.

Daytime and nighttime expansion, and how to read behavior

Comparison of daytime and nighttime expansion in Acanthastrea lordhowensis
By day it may look fine; at night it may show a more feeding-oriented and expansive side.

One of the most common mistakes is judging the coral from a single photo or at a single hour. There is a daytime reading and there is a nighttime reading. The difference between them helps you know whether the coral is comfortable, in defensive mode, or still has physiological margin.

What to look at: overall inflation, symmetry between polyps, appearance of feeding tentacles, and recovery speed after mild disturbance.
Experience — A healthy coral is not always «fully open,» but it does project confidence: it does not look shrunken, sharpened, or exhausted.

Compatibility: with fish, invertebrates, and other corals

Good compatibility

  • Reef-safe fish that do not pick at tissue.
  • Neighbors that are not too aggressive and are kept at a distance.
  • Cleanup invertebrates that do not stress it constantly.

Delicate compatibility

  • Corals with strong sweepers or pronounced chemical warfare.
  • Fish that nip fleshy LPS corals.
  • Overly dense setups where corals «touch just because.»
Tank mateRiskPractical reading
SPSLow–mediumCompatible if you are not competing absurdly for space/light.
Other fleshy LPSMediumMany «tolerate each other» until they stop. Leave margin.
Euphyllia and similar aggressive coralsMedium–highBetter not to trust luck.
Angels / nippersHighFleshy tissue is a constant temptation.

Coral ICC — coral condition index

ICC 1 · critical

Skeleton dominant / tissue collapsed

  • Skeleton highly visible.
  • Severe loss of color.
  • Polyps without useful inflation.
ICC 2 · fragile

Tissue present but thin

  • Irregular or washed-out color.
  • Tight edges.
  • Poor feeding response.
ICC 3 · target

Stable coral

  • Fleshy, inflated tissue.
  • Visible mouth but not tight.
  • Consistent color and predictable behavior.
ICC 4 · lush but monitor it

Very inflated / heavily fed

  • Striking appearance.
  • Do not confuse short-term beauty with long-term balance.
  • Avoid overfeeding just to get «more.»

Myths vs facts

MythAtlasReef fact
«The more light, the better the color.»Not necessarily. In this coral, more light can also mean more stress.
«If it isn’t fully inflated, something is wrong.»There is daytime variation, adaptation variation, and contextual variation. The trend matters, not a single photo.
«It is a passive coral.»No. It can compete and it needs space.
«It lives only from light.»No. It can capture food and benefit from a sensible feeding strategy.
«If it bleaches a little, it’s no big deal.»No. Partial bleaching is an alarm, not an anecdote.

Buying guide: what to look at before you pay

I would buy it

  • Thick, even tissue.
  • Well-defined mouths, but not collapsed.
  • Natural color, not suspiciously forced.
  • Clear polyp separation without large bare areas.

I would hold back

  • Bases with excessively exposed skeleton.
  • Very pretty color but obviously thin tissue.
  • Massively deflated polyps with no visible response.
  • Shipping damage, abrasion, or bite marks.
Experience — The best «bargain» on a tired lordhowensis often ends up being the most expensive coral in the whole setup.

Quick risk estimator

Low risk

Mature reef, moderate light, indirect flow, free space, inflated coral, and stable color.

Medium risk

Newly arrived coral, provisional position, still ambiguous behavior, irregular feeding.

High risk

Strong light, close neighbors, tight tissue, fading color, and an aquarist moving it every week.

Propagation and fragmentation

In reefkeeping, the real «breeding» you are likely to see is usually not sexual reproduction but fragmentation. That demands caution: the fact that the coral is marketable and can be cut does not mean every cut at every moment is a good idea.

Simple rule: only frag a specimen that is already clearly stable at ICC 3, and never use the saw as therapy for a coral that is already losing tissue.

Health and problems: from early warning to real loss

Acanthastrea lordhowensis with bleaching
Bleaching — still alive, but with pigment loss and a reduced safety margin.
Acanthastrea lordhowensis with retracted tissue
Early stress — less inflation and more visible skeleton.
Acanthastrea lordhowensis recovering color
Recovery — proof that acting in time really does change the outcome.
Dead skeleton of Acanthastrea lordhowensis
Exposed skeleton — at this point we are no longer talking about «something a bit off,» but about real loss.
SignalLikely readingSmart response
Paler colorLight or physiological stressReview placement before using aggressive chemistry.
Less inflationUncomfortable flow, hunger, or poor adaptationObserve the day/night pattern and the surroundings.
Retracted tissueSerious alarm but still reversibleReduce system pressure and avoid overhandling.
Skeleton dominantAdvanced damagePrioritize stability, not instant miracles.

Classic mistakes with this coral

Beginner mistakes

  • Buying for color without looking at the tissue.
  • Placing it too high from day one.
  • Assuming it is «decorative» and not reading its behavior.
  • Placing it right next to other LPS corals because «it looks good.»

Advanced mistakes

  • Trying to squeeze out color with too much light.
  • Underestimating chemical warfare or coral sweeping.
  • Overfeeding to chase extreme inflation.
  • Correcting too much at the first symptom instead of reading the trend.
Infographic of a typical error caused by too much lighting
One of the most important lessons with this coral: excess light does not equal improvement.
Critical mistake: interpreting a coral that is «less puffed up» as an excuse to tinker with everything. With LPS corals, many times the best move is to intervene little, but to intervene well.

Useful scientific and taxonomic evidence

A selection of reference sources for this profile. The goal here is not to fill the article with citations for show, but to leave a solid foundation for taxonomy, biology, and conservation context.

4) AtlasReef practical application

What do we take back to the tank? That the taxonomic change is real, that the coral is biologically more interesting than it first appears, that its natural reproduction has nothing to do with hobby fragmentation, and that the trade in colorful LPS corals exists within a broader exploitation context that deserves a deeper look.

Recommended reading

To complete the profile without leaving the AtlasReef ecosystem:

Atlasreef: Encyclopedia specialized in modern reefkeeping.

«A good lordhowensis is not measured only by the color it shows. It is measured by the calm way it lives within the system.»

— atlasreef

FAQ — frequently asked questions

Is it easy or difficult?

It is easier than many SPS corals, but it is not a «place it and forget it» coral. Its real difficulty lies in reading the tissue closely and choosing the right placement.

Does it need direct feeding?

Not always, but it can benefit from a sensible feeding strategy, especially during recovery or to support fleshy tissue.

Can it bleach even if the parameters are «fine»?

Yes. Light, flow, transport, aggression from neighbors, or a combination of factors can trigger color loss even when the numbers look correct.

Should I place it on the sand or on rock?

Both can work depending on the setup, but always with stability and while avoiding unnecessary exposure to light or aggressive sweeping.

Is it still correct to call it Acanthastrea lordhowensis?

In hobby language people will understand you, but the accepted name today is Micromussa lordhowensis.

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