Plate Coral Care Guide (Fungia sp.)
The plate coral is one of the most charming and approachable corals in the reef hobby, and a lovely introduction to keeping LPS corals. LPS stands for large polyp stony, a group of hard corals that build a solid stony skeleton out of calcium carbonate but carry a soft, fleshy, often quite large polyp over the top of it. Plate corals belong to a family of stony corals known as the fungiids, a group of plate and disc shaped corals that includes several closely related species. In the aquarium trade you will most often meet them as Fungia and Cycloseris, along with relatives such as Diaseris, Lithophyllon and the long tentacle Heliofungia.
What sets this group apart is that a plate coral is a single, solitary animal that lives loose on the sand rather than cemented onto the rock. It is one polyp, one mouth and one round disc of skeleton, and quite remarkably it can inflate itself with water and shuffle across the sand under its own power. This guide focuses on the short tentacle plate and disc corals in the Fungia and Cycloseris group, the ones most hobbyists simply call plate or disc corals.
1. Species Overview
A plate coral looks just as the name suggests. It is a rounded, slightly domed disc of stony skeleton, marked along its ridges by fine radiating ribs called septa that fan out from a central mouth like the spokes of a wheel. Fungia species tend to be the larger of the two you will see most often, growing into broad plates, while Cycloseris are usually smaller, finer ribbed and a little more domed and button like. Both are solitary, meaning each is a single individual rather than a colony of joined polyps, and both come in a spectacular range of colours, from neon greens and oranges through to reds and golds.
In the wild these corals live across the Indo Pacific, settling into the rubble and sand zones of the reef rather than the solid rock. They start life attached by a small stalk, but as they mature they detach and spend the rest of their lives free living on the substrate. Like most reef corals they carry a population of zooxanthellae, tiny symbiotic algae that live inside the coral’s own tissue and use light to produce sugars that feed the coral. This makes a plate coral part solar powered and part hunter. Most endearing of all is their ability to move: a plate coral can puff its body up with water, sometimes to nearly twice its resting size, and use that inflation to walk across the sand, climb a gentle slope, shed debris, or flip itself back over if it is turned upside down.
2. Difficulty Level and Suitability
Plate corals are rated as a beginner coral, and deservedly so. They are hardy, forgiving of the small swings that happen in any young tank, undemanding about light and flow, and they take prepared foods eagerly. For someone moving on from soft corals to their first LPS coral, a healthy short tentacle plate is one of the best choices on the shelf. They ask only for a stable tank, a patch of open sand, gentle water movement and the occasional meal.
Two honest caveats are worth knowing up front. The first is that the closely related long tentacle plate coral, Heliofungia, is the tricky exception in this family. It looks similar but has a reputation for doing well at first and then declining suddenly, so it is not a beginner animal and is not what this guide describes. The short tentacle Fungia and Cycloseris are far more forgiving. The second caveat is handling: these corals have soft, exposed tissue over a stony skeleton and dislike being handled roughly, dropped, wedged into gaps or left to tumble in strong flow. Treat the coral gently and give it an open spot on the sand, and it will settle in without fuss.
3. Water Parameters
Plate corals appreciate the same clean, stable, natural seawater conditions that suit most LPS corals. Stability matters far more than chasing any single perfect number, so aim to keep these values steady. The figures below match the parameters we recommend across our reef livestock.
| Parameter | Target range |
|---|---|
| Salinity | 1.025 to 1.026 specific gravity (about 35 ppt) |
| Calcium | 400 to 450 ppm |
| Alkalinity | 8 to 9 dKH |
| Magnesium | 1250 to 1350 ppm |
| Nitrate | 5 to 15 ppm (low but not zero) |
| Phosphate | 0.03 to 0.10 ppm (low but not zero) |
| Temperature | 24 to 27 degrees Celsius |
| pH | 8.1 to 8.4 |
A few of these terms are worth unpacking. Specific gravity is a measure of how dense your salt water is compared with fresh water, a convenient way to check how salty the tank is. Alkalinity is measured in dKH, or degrees of carbonate hardness, and reflects the water’s ability to hold a stable pH while supplying the building blocks a stony coral needs for its skeleton. Calcium, alkalinity and magnesium work together, and a plate coral draws on all three to build its skeleton, so keeping them balanced and consistent is the goal.
Notice that we list nitrate and phosphate as low but not zero. These are nutrients, and while very high levels cause problems such as algae and browning, stripping them all the way to zero is just as harmful. A plate coral relies on its zooxanthellae, and those algae need a small, steady supply of nutrients to keep the coral’s colours rich. A tank scrubbed completely bare can leave a plate coral pale and starved, so a little of each is a good thing.
4. Lighting Requirements
Plate corals are moderate light corals and not at all fussy, which is part of what makes them so beginner friendly. Because they live on the sand rather than up on the rockwork, they naturally sit in a lower light zone of the tank and are perfectly happy there.
Light for corals is usually described in terms of PAR, which stands for Photosynthetically Active Radiation. In plain terms, PAR measures how much usable light actually reaches the coral, the portion its zooxanthellae can use to make food. Plate corals do well across a broad, forgiving band of moderate lighting, and roughly 50 to 150 PAR at the sand suits them nicely, and there is no need to blast them. Too much intense light can bleach a plate coral, causing it to expel its zooxanthellae and pale out, so keep them out of the very brightest spot directly under a strong light. If your coral came from a dimmer system, acclimatise it gradually over a couple of weeks, starting in a shadier corner of the sand and moving it into more light only if it seems to want it. Comfortable, even, moderate lighting gives the best balance of colour and health.
5. Flow Requirements
Gentle water movement is the rule for plate corals. They prefer low to moderate flow, and the key word is gentle. In the wild they rest in calmer, sheltered pockets of sand and rubble, and they want the same in the aquarium: enough movement to carry away waste and bring food past them, but never a strong, direct jet blasting onto their tissue.
Too much flow causes real problems. If you see the fleshy tissue pushed flat and drawn tightly against the stony skeleton on one side, or the coral being nudged and rolled around, that is a clear sign the flow is too strong and needs softening or redirecting. Persistent strong current can wear away the delicate tissue and open the door to infection. Aim instead for a soft, indirect, almost random drift of water across that part of the sand bed, and position the coral where sand is not constantly blown onto it, since a steady sprinkling of grains irritates the tissue over time.
6. Feeding
Plate corals are enthusiastic, rewarding feeders. Although they gain much of their energy from light through their zooxanthellae, they are also genuine predators that readily take meaty foods, and feeding them well keeps them plump, colourful and growing.
Plate corals feed most naturally at night. After the lights go out the coral extends a fringe of short feeding tentacles across its surface, and this is the ideal time to offer food. You do not have to wait for darkness every time, as many will grab a meal during the day once they learn the routine, but night is when their feeding response is strongest. Suitable foods include mysis shrimp, enriched brine shrimp, finely chopped prawn or fish, small pieces of silverside, and good quality sinking pellet or LPS coral foods. Target feed gently with a turkey baster or feeding syringe, placing a morsel directly onto the surface near the central mouth, ideally after turning the pumps off for a few minutes so the food is not swept away.
Feeding two to three times per week is plenty, and there is no benefit to overdoing it. Overfeeding fouls the water and can stress the coral, so a modest, regular schedule of small meals beats large or constant feeding. A plate coral fed a couple of times a week under moderate light will grow noticeably faster and hold better colour and body than one left to rely on light alone.
7. Placement and Aggression
Placement is refreshingly simple: put the coral on the sand bed. These are free living corals meant to rest flat on the substrate, mouth facing up, on an open patch of sand or fine rubble on the floor of the tank. Do not perch them on the rockwork and, most importantly, never wedge them into a gap or crevice between rocks. Wedging is a common and genuinely harmful mistake, because it prevents the coral from inflating and self cleaning and leaves the tissue grinding against hard rock every time it shifts. Remember too that a plate coral does not necessarily stay where you put it, and over days and weeks it may slowly walk itself to a spot it prefers, so plan for a little wandering when you choose its neighbours.
In temperament, plate corals are largely peaceful and among the more easy going corals to place. They will not go looking for a fight. Even so, they are not defenceless. Like many LPS corals they can extend some longer tentacles at night, sometimes called sweeper tentacles, which are elongated stinging tentacles a coral puts out to sting and clear space around itself. They can also release a slippery mucus when stressed or crowded, and that slime can irritate or damage the tissue of a neighbour it touches. Combine that with their habit of slowly moving, and the sensible approach is to give a plate coral clear open space on the sand, several centimetres of buffer on all sides, so it cannot contact other corals as it settles or wanders. Give it that room and it will coexist happily with the rest of the reef.
8. Growth Rate and the Colouration Versus Growth Trade-Off
Because a plate coral is a single solitary polyp rather than a branching colony, its growth shows up as the whole disc slowly getting larger and thicker rather than as new branches or heads. Growth rate varies between species and individuals, from quite slow to moderate, with a well fed, well lit specimen thickening and widening its plate over the seasons. Give it stable conditions and regular food and it will fill out in its own time.
It is worth understanding the gentle trade off between colour and growth, because the conditions that push maximum growth are not always the ones that bring out the most intense colour. Broadly, slightly leaner nutrients paired with good, steady light tend to encourage the deepest, most saturated colouration as the coral’s pigments concentrate. A little more nutrient along with regular feeding tends to favour faster tissue growth and a fuller, plumper body, sometimes at the cost of that ultra vivid colour. Neither is right or wrong; it depends on whether you most want a fast growing, robust coral or a slower, jewel bright showpiece. For a plate coral the happy middle ground is easy to find, since stable parameters, moderate light and a couple of feeds a week give strong colour and healthy growth together. Small, deliberate adjustments let you nudge the balance to suit your goals.
9. Common Issues and Troubleshooting
Plate corals are hardy, but almost every problem they run into traces back to damaged tissue, so protecting that soft body is the heart of good plate coral care.
Tissue damage and recession. The most common issue is physical damage to the fleshy tissue, whether from rough handling, being wedged against rock, tumbling in strong flow, or sand constantly blown onto it. Damaged tissue often recedes, pulling back to expose the white skeleton underneath. Small areas can heal if the cause is fixed quickly, so review flow, placement and handling straight away if you see recession starting.
Infection and brown jelly. Tissue damage is so serious because an open wound can quickly become infected. A common, fast moving infection is brown jelly, a brown, slimy, jelly like film that creeps across the tissue, usually starting at a damaged edge and spreading inward. It can consume a coral rapidly, so act at the first sign: move the coral to a separate container, baste the brown slime off, and use a coral safe iodine dip to disinfect the tissue before returning it to a clean, calm spot.
Rough handling. Plate corals can be sensitive if handled roughly, so always move them with care. When you need to lift one, support the whole stony disc from underneath with your fingers on the skeleton rather than gripping the soft flesh, and set it down gently on the sand. Avoid lifting it out of the water more than you must, and never let it get pinched or dropped.
Dead spots on a bare bottom. If a plate coral is left sitting on bare glass or a very hard surface with no substrate, the underside can develop a dead patch where it cannot clean itself, and that dead spot can become a site of infection. Giving it a proper sand bed to rest on largely prevents this.
Not opening or staying deflated. A plate coral that stays shrunken and refuses to inflate for an extended period is telling you something is off. Check that parameters are stable, look for too much flow or light, make sure it is not being stung by a neighbour, and confirm it has an open, calm spot on the sand. Once the irritation is sorted, it usually puffs back up and resumes its normal, gently pulsing appearance.
Pests. Damaged or receding tissue can attract opportunistic pests such as bristleworms that move in on the weakened area. The pests are usually a symptom rather than the root cause, so the priority stays the same: protect the tissue, keep the coral on clean sand, and address any damage promptly.
A Note on the Ranges Above
The water parameters and other figures in this guide are a general guideline only. Every reef is different, and the ideal balance depends on your lighting, your other livestock and how you run your system. For a more in-depth, personalised look at what favours colouration versus growth for this species in your particular tank, have a look at our Growth vs Coloration Calculator.
Disclaimer
This guide is provided for general educational purposes only. It is not a substitute for professional veterinary or aquatic health advice, and we cannot guarantee outcomes. Individual corals vary, and the right conditions for your system depend on your lighting, your equipment and the other livestock you keep. If you are unsure about anything, please get in touch with our team before proceeding.