Montipora Care Guide: Light, Placement, Pests and Why Montis Turn White or Brown

A red plating frag goes on the top rock, right under the new light, because that is where the pretty ones go. Ten days later the edge is white and the rest is going pale. Montipora is the easiest stony coral most people will ever keep, and nothing was wrong with that tank’s water. The problem was placement, which is the part of monti care nobody writes on the label.

This guide covers montipora from the first frag to a plate the size of your hand: the three growth forms, how much light each one wants, where to put it, flow, water, the nudibranch that eats nothing but montis, and what white or brown color is telling you. If a new coral of any kind hasn’t opened since it arrived, read new coral not opening after shipping first.

What montipora is

Montipora is a small-polyp stony coral (SPS) in the same family as Acropora. It has the smallest corallites of any coral family, under 1/12 inch across, which is why a healthy monti looks like fuzzy velvet with its polyps out and like smooth colored stone with them in. There are more than 85 described species.

None of them are native to Florida. Montipora lives across the Red Sea, the Indian Ocean and the Pacific, and it is absent from the Atlantic entirely. Every monti a Florida reefer buys is either imported or grown in captivity. Most of the trade is captive-grown now. As Michael Paletta has pointed out, aquacultured frags became the norm after many exporting countries closed to wild coral at one time or another.

Montis come in three shapes, and the shape decides most of the care:

Form	Common examples	Where it goes	Starting PAR
Plating	M. capricornis (“caps”), red and green caps	Low to middle, nothing slow-growing underneath	125 to 150
Encrusting	Rainbow, Superman-type and most “designer” montis	Low to middle rock, room to spread	100 to 150
Branching	M. digitata, M. setosa, spy monti	Middle to upper rock, open space around it	125 to 150, can go much higher

One colony can show more than one form, and light pushes it one way or the other. Reef Builders’ Jake Adams found that in M. capitata, bright light drives upright branches and dimmer light drives scroll-shaped plates.

Two branching montis from the table: an Orange Setosa and a spy monti.

Light: start low, then earn the color

Tidal Gardens, a coral farm, starts new pieces around 125 to 150 PAR and raises it slowly. In its systems montis did best at about 200 to 300 PAR. Dana Riddle’s measurements show how wide the survivable range is: orange M. digitata handled up to 700 µmol in one case but did fine at 144, while an encrusting monti sold as Superman bleached at only 300 on an 11-hour day.

So the range a monti can survive is wide, and the range where it looks its best is narrower. Color follows light. A 2008 study that included corals from montipora’s family found the green and red fluorescent pigments are nearly absent in very low light and build as blue-heavy light increases. In practice:

• Too little light: the monti keeps growing but turns brown. Riddle’s Superman grew well at 100 µmol for four months and lost its purple.
• Too much, too fast: the edges go white first, then the whole piece pales. Tidal Gardens warns that a day or two under strong light can seriously damage a coral grown under moderate light.

A new monti should go in low, stay there for a couple of weeks, and move up in steps. Moving it around after that sets it back each time; Paletta says a coral needs at least two to three months to adjust to a new spot. If you don’t know your PAR, a meter reading beats any vendor’s “medium light” label. The labels disagree from one seller to the next, so trust the number. Our reef tank lighting guide covers how to read one.

Montis from our tanks.

Placement and spacing

Plating montis grow fast and grow outward. Paletta’s rule is to keep them in the lower part of the tank and never above slow-growing corals, because a cap that plates over another coral starves it of light. Encrusting montis creep across rock and up the bases of neighbors. Branching montis want open water around them so flow reaches every branch.

Montis rarely sting, but they are not harmless neighbors. Riddle watched different color morphs of M. digitata fight: green beat the other three colors, orange beat purple, and brown lost to everyone. Give different montis about an inch of space and watch the contact line if they touch. Keep LPS and anything with sweeper tentacles well away, since those will sting the monti.

Flow

Moderate to strong flow, with some randomness to it. Riddle’s test is simple: the polyps should rock gently. If they flatten or pull in, the flow is too hard; if detritus settles on the coral, it is too soft. Plates need flow underneath too. The shaded space under a cap is where detritus and pests collect, so blow it out with a turkey baster when you do tank maintenance.

Water: stable matters more than perfect

These targets start from Randy Holmes-Farley’s recommended reef ranges:

Parameter	Target
Alkalinity	7 to 11 dKH, held steady
Calcium	380 to 450 ppm
Magnesium	1,250 to 1,350 ppm
Temperature	About 76 to 80°F, held steady
Salinity	35 ppt (1.026 specific gravity)
Phosphate	Low but measurable, around 0.01 to 0.03 ppm
Nitrate	Low but measurable, never zero

The swing is what hurts. A growing colony pulls calcium and alkalinity down much faster than a tank of soft corals, so once your montis start plating out, plan on regular testing and a dosing routine instead of occasional big corrections. Details are in our reef tank water parameters guide.

Don’t strip nutrients to zero chasing color. A 2013 study in Nature Climate Change found that nitrogen with too little phosphate makes corals more likely to bleach from heat and light, because the algae living in the coral run short of phosphate. High phosphate dulls color; no phosphate starves the coral. Aim for the middle.

Test calcium, alkalinity and magnesium, and dose to hold them steady.

Feeding

Montis get nearly all their food from light. A tank with fish being fed provides enough, and there is no need to target-feed a monti. Light broadcast feeding is optional. More food mostly means more algae.

Montipora-eating nudibranchs

This is the one pest every monti keeper should know on sight. Phestilla subodiosus, named in 2020, eats Montipora and almost nothing else. The adults are 1/16 to 1/6 inch long, white with brown speckles, and they hide on the underside of the colony where it meets the rock or plug. The researchers who described it got their specimens from montipora frags bought at aquarium stores and traded between hobbyists, which is how it gets into tanks.

The damage looks like tissue loss spreading from the bottom of a plate. People often blame their water. Before you change anything, flip the plate or lift the frag and look underneath with a flashlight.

Two more things. Beneficial Berghia (the aiptasia eaters) look very similar, so don’t panic over a white nudibranch on an aiptasia. And some keepers add wrasses hoping they will eat these nudibranchs; no study has confirmed that they do. Our coral dipping guide covers the dip itself, and coral pests 101 covers the rest.

A dip kills adult nudibranchs, not their eggs. Check under the plate as well.

Why is my montipora turning white or brown?

White or pale

In rough order of how often it happens:

1. Too much light, too fast. Move it down or drop the intensity.
2. Heat. Check the temperature and the heater.
3. Nutrients bottomed out. Zero phosphate with nitrate present is a bleaching risk.
4. Nudibranchs. White skeleton spreading from underneath, not from the top.

A pale monti with tissue still on it can color back up once the cause is gone. Bare white skeleton has no living tissue left. At best, healthy tissue next to it will slowly grow back over it.

Brown

Usually too little light, too much phosphate, or both. Raise light in 10 to 20 percent steps, bring phosphate down toward 0.01 to 0.03 ppm, and wait weeks, not days. Color comes back slower than it leaves.

Tissue receding

Look underneath for nudibranchs first. Then check alkalinity for a recent swing. If it keeps going, cut the healthy tissue off and glue it to a new plug, and keep it away from your other montis until it stops. Our bleaching vs. STN vs. RTN guide explains how to tell the three apart.

Fragging montipora

Tidal Gardens calls montis one of the easiest corals to break apart and reattach, and they are. For a plate, cut or snap a wedge from the edge with bone cutters; the growing edge carries the best color. For an encrusting monti, cut the rock under it or saw off a strip. For a branching monti, clip a branch and glue it into a drilled plug.

Size matters for survival. From his own experience and other hobbyists’, Paletta puts survival at about 25 percent for a 1/2-inch frag, about 50 percent at 3/4 inch, and 75 percent or better at 1 inch. Those are his estimates, not a study, but they point the right way: cut bigger pieces than you think you need. Dip every new frag and check it for eggs before it goes back in.

Monti frags from our listings, and CorAffix for mounting your own.

Quick answers

Is montipora easy to keep?

It is the easiest SPS for most people, with one condition: the tank has to be stable. Give it a system that has been running at least six months. Caps, digitata and setosa are the most forgiving.

Is montipora SPS or LPS?

SPS. It is a small-polyp stony coral in the Acroporidae family.

Do montipora sting?

Not in any way that matters. The risk is overgrowth and shading, plus fights between some color morphs.

Can you dip montipora?

Yes, and you should. Montis handle standard dips well. Remember the dip does not kill nudibranch eggs.

How fast does montipora grow?

Fast for an SPS. A frag in good conditions will visibly plate, spread or branch within a few months. We couldn’t find a reliable inches-per-month figure for home tanks in any published source, so treat any specific number with suspicion.

Do all montipora plate?

No. There are plating, encrusting and branching montis, and light changes the shape of all three.

Sources

• Tidal Gardens, montipora coral care and coral pests
• Dana Riddle, Montipora digitata: a stony coral for all hobbyists and Superman montipora, Reefs.com
• D’Angelo et al. (2008), light and coral fluorescent pigments, Marine Ecology Progress Series
• Wiedenmann et al. (2013), nutrient imbalance and coral bleaching, Nature Climate Change
• Wang et al. (2020), Phestilla subodiosus, the montipora-eating nudibranch, ZooKeys
• Michael Paletta, Reef Builders: coral placement, reef tank pests and buying frags
• Jake Adams, Reef Builders, Montipora capitata
• Randy Holmes-Farley, reef aquarium water parameters, Reefkeeping

The Underwater Gardener grows aquacultured corals in Key West, Florida (FL Aquaculture Certificate #AQ0254072). Our corals are raised under stable reef lighting in our own systems, so they arrive already adapted to a well-run tank. Corals ship UPS Next Day Air every Tuesday and Wednesday.