New Coral Not Opening After Shipping: What’s Normal and What Isn’t

The box came on time. The heat pack was still warm, the bags had not leaked, and the coral inside is a tight, sullen lump that looks nothing like the photo you bought. This is the most common message we get, and in most cases the honest answer is that nothing is wrong yet. Here is how to tell the difference, and what actually helps in the first five days.

Why is my new coral still closed after shipping?

A coral that arrives closed is responding to the trip, not to your tank. It has spent 18 to 30 hours in total darkness, in a sealed bag whose water has been slowly acidifying, warming or cooling, and running out of oxygen. Pulling the polyps in is the cheapest defensive move a coral has. If the tissue still covers every part of the skeleton, the animal is intact and sulking. The mistake almost everyone makes is watching the polyps. Polyp extension is a mood, not a vital sign. A torch can stay balled up for four days and be perfectly healthy, and an Acropora can have its polyps out while its base quietly dissolves. The thing worth watching is the tissue line.

How long should a new coral stay closed?

Most corals show something within 24 to 48 hours and look normal by day three to five. Softies and leathers take the longest and often shed a waxy mucus coat first. Below is what growers consistently report, ordered fastest to slowest.

Coral	First sign of life	Looking normal
Mushrooms, ricordea	Hours to 1 day	1 to 2 days
Zoanthids, palythoa	1 day	2 to 4 days
Euphyllia (torch, hammer, frogspawn)	1 to 2 days	3 to 5 days
Acanthastrea, micromussa, favia	1 to 2 days	3 to 5 days
Plates (Fungia, Cycloseris)	1 to 3 days	3 to 7 days, variable
Acropora and other SPS	Judge by polyp extension, 1 to 3 days	5 to 10 days for color
Leathers (Sarcophyton)	3 to 7 days, after a shed	1 to 2 weeks

Sarcophyton deserves its own warning. Reef Builders puts it bluntly: do not be alarmed when, not if, a newly moved leather closes up for days and develops a waxy film, which it then sheds before the polyps come back. People throw away perfectly healthy leathers over this every week.

What actually happens inside a shipping bag?

The animal respires, so oxygen falls and carbon dioxide rises. Dissolved CO2 forms carbonic acid, so the pH drops. At the same time, ammonia from respiration and decomposing mucus accumulates. Those two curves move in opposite directions, and that turns out to be the saving grace, because the falling pH keeps the accumulating ammonia locked in its harmless form. A study of marine ornamental fish shipped for 24, 48 and 72 hours found that pH and oxygen, not ammonia, predicted mortality. Ammonia buildup was not the problem even at 72 hours. A careful hobbyist test of invertebrate bags after 28 hours in transit measured up to 25 ppm total ammonia at pH 7.4, of which only about 0.1 to 0.3 ppm was in the toxic free form. Coral bags carry far less waste than a bag of turbo snails, and corals actively consume ammonium as a nitrogen source. Real coral bags on a one-night transit usually land somewhere around pH 7.6 to 7.9 with total ammonia under 2 ppm. Not nothing, but not the poison bath the hobby imagines.

Should I drip acclimate a coral?

No. Float the sealed bag for 15 to 20 minutes to match temperature, then lift the coral out by its plug or rock and put it in the tank. Do not pour the bag water in, and do not spend two hours dripping. The whole process should take under half an hour. The chemical argument against dripping is real. Ammonia exists in two forms, ammonium (NH4+, largely harmless) and free ammonia (NH3, toxic), and the split between them is set almost entirely by pH. When you slowly raise low-pH bag water toward tank pH, you convert ammonium into free ammonia without adding a single molecule of nitrogen.

Work it through with a real bag. Two parts per million of total ammonia at pH 7.4 and 78°F is 0.024 ppm of free ammonia, comfortably below the 0.05 ppm level at which people start worrying. Drip that same water up to pH 8.2 and it becomes 0.141 ppm, roughly six times higher, heading toward the 0.2 ppm alarm threshold. Nothing was added. The pH did it.

What should I do in the first hour?

1. Lights off before you open the box. The coral has been in the dark for a day. Full reef lighting on arrival is the single harshest thing you can do to it.
2. Float the sealed bag 15 to 20 minutes. Temperature only. Do not open it in the tank.
3. Lift the coral out by the plug or rock. Never by tissue. Bag water goes down the sink.
4. Place it low and shaded, in gentle indirect flow. The bottom of the tank or a frag rack near the sand. Enough flow to keep shed mucus moving, not enough to bend it.
5. Leave the lights off until the next morning. Then run them low.
6. Take a photograph. Same angle, ordinary white light, with something for scale. This is the most useful thing you will do all week.

Is my coral sulking or is it dying?

Look for exposed skeleton, not closed polyps. A sulking coral has tissue over every millimeter of its skeleton, normal or slightly pale color, and looks the same today as it did yesterday. A coral in trouble has bare white skeleton where tissue used to be, and the boundary between the two moves measurably between one photo and the next.

This is why the daily photograph earns its keep. Brown jelly syndrome consumes tissue at a measured 15 to 20 square millimeters per day, and some white syndromes advance far faster. A static line over 24 hours is sulking. A line that moved is necrosis, and it will not stop on its own.

What you see	What it usually is	What to do
Closed polyps, tissue intact	Normal shipping stress	Nothing. Wait.
Stringy clear mucus	Normal. Corals shed after handling.	Gentle flow to carry it away
Pale or washed out color	Light shock or mild bleaching	Shade it further, feed the tank
Brown gelatinous film, tissue vanishing under it	Brown jelly	Remove, dip, frag above the line, isolate
Tissue peeling off in sheets overnight	Rapid tissue necrosis	Remove from the display immediately
Bleaching creeping up from the base over days	Slow tissue necrosis	Frag above the line, review parameters
Detached polyps sitting on the sand	Polyp bailout	Check temperature and salinity now

Two corrections worth carrying with you. Brown jelly is still widely blamed on an organism called Helicostoma nonatum; sequencing work points instead to ciliates in the genus Philaster, and the name has simply been passed down. And polyp bailout is not a mild sign. In controlled work it required six days of heating to 34°C before polyps detached, so if you are seeing it, something in the tank is badly wrong and the shipping is not the cause.

How much light should a newly shipped coral get?

Start at roughly a third to a half of the coral’s normal target PAR, and step it up over two to four weeks, holding each step about a week. That week is not arbitrary. Measured photoacclimation in corals shows the saturation irradiance settling to a new stable level over five to ten days after a change in light, with no shortcut in either direction.

Coral	Normal PAR	First week after arrival
Zoanthids, mushrooms, ricordea	50 to 150	30 to 60
Leathers	100 to 150	40 to 70
Euphyllia, acans, favia	100 to 250	50 to 90
Lobophyllia, chalices	150 to 200	50 to 80
Acropora, montipora	200 to 300	80 to 120

If your fixture will not dim far enough, stack cut circles of mesh window screen on the glass lid above the coral and pull one layer off each week. It is crude and it works. The full ramp logic is in our reef tank lighting guide, and if you do not own a PAR meter, we rent one in the shop for 75 dollars for two days against a refundable deposit.

Should I dip a coral the day it arrives?

Wait a day if you can, dip on arrival if you cannot. This is one of the few places where reputable growers openly disagree, and the disagreement is not about coral biology. It is about which risk you are more exposed to. World Wide Corals advises waiting 10 to 24 hours and states that improper dipping is the single largest cause of dead corals they see. Tidal Gardens and Pacific East put the dip inside the acclimation sequence, before the coral touches the system. Both positions are defensible, and the resolving variable is simple: if you have a quarantine or frag tank to hold the coral for 24 hours, wait. If it is going straight into your display, dip first, because otherwise you are knowingly putting an unscreened animal into your reef. Dips are not free either way. In a controlled test on Goniopora, a 1.5 percent potassium chloride dip killed the offending ciliates in about 90 seconds with 100 percent coral survival, while hydrogen peroxide at comparable strength visibly stressed the coral. Follow the dose on the bottle, keep it short, and rinse in clean tank water afterwards. Our full method is in how to dip corals, and what you are actually hunting for is in coral pests 101. Two Little Fishies ReVive Coral Cleaner — 500 ml$13.49 · The dip we use on everything that comes through the door

When should I start feeding it again?

Not while it is closed. A retracted coral cannot catch food, and uneaten food rotting on a stressed animal is exactly the substrate that bacterial and ciliate problems need. Wait until polyps or tentacles are visibly extending, then start with broadcast feeding the tank rather than spot feeding the new arrival directly. Once it is open and reaching, targeted feeding genuinely speeds recovery, particularly for LPS that lost tissue mass in transit. The method matters more than the product; see spot feeding corals. Red Sea Reef Energy Plus AB+ Coral Superfood — 500 ml$30.99 · Broadcast food for the whole tank while a new coral finds its feet

What if it does not come back?

Photograph it every day from the same angle for the first five days, and keep the packing slip in frame. That single habit does two jobs: it is the diagnostic tool from the section above, and it is the evidence every live arrival guarantee in this industry asks for. There is no industry standard “48 hour rule” despite how often you will read it. Real windows run from two hours to five days depending on the vendor, so read the one you actually bought from. A few things that quietly void coverage almost everywhere: refusing delivery because the box looks damaged (accept it and document instead), removing the coral from its plug during the window, and discarding the specimen before the vendor has seen it. Red Sea Ammonia Test Kit$26.99 · Worth having on the shelf before you need it, not after

Why ours tend to open faster

We grow our corals in Key West, in our own systems, under stable reef lighting. They are not wild colonies that were collected last week, bagged, flown across an ocean, held at a transshipper and then bagged again. Most of ours have never left the building before the day they are packed for you, which means the trip to your tank is the first serious stress they have experienced, not the fourth. It also means they are already adapted to the light and the parameters of a well-run closed system rather than a reef flat. That does not make them immune to a hard shipment, but it does shorten the recovery, and it is the main reason we can be relaxed about telling people to leave a closed coral alone for five days. Beginner LPS Mystery Pack — torch, hammer, acan, favia, chalice$249.00 · Five aquacultured LPS, all forgiving of a slow start Zoa Mystery Starter Pack — 5 aquacultured zoa and soft coral frags$99.00 · The fastest category to reopen after a shipment Still not sure what you are looking at? Send us the photo. We would rather talk you down from a healthy coral than have you throw one away, and if it genuinely is going wrong we will tell you that too. Browse what is in stock right now, or come see the farm at 2816 North Roosevelt Blvd in Key West.

Related. If a new coral will not open, it is worth knowing what it went through before the box. Why the cheapest coral costs the most traces the chain from reef to your tank and where the losses hide.

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.