Scolymia Care Guide: Feeding, Light, Placement and Why Scolys Cost So Much

A new scoly goes onto the sand bed, swells to twice its size by evening, and grabs every piece of mysis you give it. Six months later it is a little smaller every week, and nothing on the test kit explains why. Leonard Ho described exactly that pattern in 2012: scolys that fed and extended well for months, then slowly faded. Nobody has pinned it to one cause, but the likely ones are things you control.

This guide covers what a scoly actually is, where it comes from, and what that means for light, placement, flow, feeding and water. It also covers why tissue recedes, how scolys are propagated now, and why they cost what they do. If you are comparing scolys with other big fleshy corals, our Acanthophyllia guide covers a close cousin.

What a scoly is

Almost every “scoly” or “Australian scolymia” sold in the U.S. is Homophyllia australis, a single-polyp stony coral in the family Lobophylliidae. It was moved out of the genus Scolymia in 2012, and the trade kept the old name because nobody wanted to call their best coral a “Master Homo,” as Reef Builders’ Jake Adams put it.

True Scolymia still exists, and it lives only in the Atlantic: Florida, the Bahamas, the Gulf of Mexico, the Caribbean and Brazil. There are thousands of records of it on Florida reefs. Florida law (Florida Administrative Code 68B-42.009) bars anyone from taking or selling stony coral from state waters, so those corals stay on the reef. Every scoly for sale in Florida is an import, almost always from Australia, and anyone selling one must be able to show the paper trail back to where it was harvested.

A few look-alikes come up in searches:

Coral	What it is
“Scoly,” Australian scolymia	Homophyllia australis, single polyp
“Bankies”	Homophyllia bowerbanki, the colonial cousin with many small polyps
“Flat scoly,” Scolymia vitiensis	Now Lobophyllia vitiensis, from Fiji, Tonga and the Solomons
Acan, Acanthophyllia, Cynarina	Same family as the scoly, different genera
Trachy (open brain)	A different family, Merulinidae

Where they come from, and why it matters

Two facts from the source change how you should keep one.

First, the trade stock is not collected from calm lagoons. Monsoon Aquatics, an Australian exporter, collects scolys between Mackay and Gladstone in Queensland off a deep vertical wall at 92 to 98 feet, in currents of 1.5 to 3 knots strong enough that divers sometimes need a rope from the boat. Every piece they collect is weighed and reported to fisheries managers, and for some corals the quotas go down to the species.

Second, most museum and field records of H. australis come from cooler southern Australia, including South Australia, Victoria and even Tasmania. That fits advice from ACI Aquaculture’s Chris Meckley that scolys “fare better” at 74 to 76°F.

So a scoly lives in dim light, strong but broad current, and relatively cool water. In a tank that translates to low light, flow that moves past it without blasting it, and a temperature at the cooler end of the reef range.

Light and placement

Tidal Gardens, a coral farm, puts it plainly: “anything around 100 PAR is adequate for their health.” Their product pages recommend low to moderate light, which they define as 30 to 150 PAR. A working target is about 50 to 150 PAR, around 100, and lower for the first couple of weeks after it arrives. Tidal Gardens finds color depends more on the light’s spectrum than on its strength, and too much light can bleach a scoly and wash out the patterns that made it expensive.

Put it low: on the sand bed or a broad, flat rock near the bottom. Sources differ on the angle. Reef Builders recommends flat and facing straight up for even light. Tidal Gardens prefers a slight tilt so waste runs off the mouth. Either works. What doesn’t work is a narrow rock ledge where the inflated flesh hangs over an edge, rubs on rock or can fall.

If your fish kick sand around, raise the scoly a little. A mouth full of sand can’t feed.

Flow

Gentle to moderate, and indirect. Tidal Gardens aims for “just enough flow to carry away waste from their mouth.” The wild current is strong, but it sweeps across a wall. A powerhead aimed at one spot folds and tears inflated flesh, blows food off before it can be eaten, and keeps the coral from opening. If the flesh is rippling or pinned to one side, move the scoly or turn the pump.

Feeding

Scolys are photosynthetic, but they also catch food, and in a single-polyp coral there is no colony to share the load. Feeding makes more difference with a scoly than with most corals.

• What: meaty foods such as mysis, brine shrimp and fine chopped seafood. Tidal Gardens also uses commercial pellets and powders.
• How often: one to three times a week, in small portions. Feed more often if the coral is new or looks thin.
• When: in the evening, when the feeding tentacles come out, and after the fish have eaten.
• How: turn off the pumps, place the food on the mouth, and wait until it is taken in. Then baste away anything left on the flesh, because leftover food rots and burns the tissue.

If fish or shrimp keep stealing the food, many keepers set a clear cup over the scoly while it eats. More on technique in our spot feeding guide.

A target feeder puts food on the mouth with the pumps off.

Water: steady and on the cool side

Parameter	Target
Temperature	74 to 78°F, cooler end preferred
Salinity	1.025 to 1.026 specific gravity
Alkalinity	8 to 9 dKH, held steady
Calcium	400 to 450 ppm
Magnesium	1,250 to 1,350 ppm
Nitrate	About 2 to 10 ppm
Phosphate	Low but not zero

Tidal Gardens finds that nitrate around 5 to 10 ppm is welcome for large-polyp stony corals, but that around 30 to 40 ppm you start to see tissue recession. See our reef tank water parameters guide for how to hold these numbers steady.

Common problems

Tissue receding from the skeleton

Scott Shiles, writing about the related solitary corals in Reef Builders, lists the usual physical causes: rubbing on rock, being blasted by direct flow, collapsing onto rough substrate, and being stung by a neighbor. Add high nitrate and rotting food left on the flesh. Check all of those before blaming the coral. Tissue loss usually shows first at the rim as bare white skeleton, so look at the edge and the underside every few days.

Not inflating

When a scoly stays deflated for days, look first for something that changed: a new spot, a jump in light, a pump now hitting it, a fish picking at it at night, or a big swing in the water. Undo the most recent change first.

Brown jelly

Brown, slimy mucus with tissue breaking down quickly, usually after shipping stress, physical damage or poor water. Move fast: siphon it off and dip the coral.

Fish and inverts that pick

Many dwarf angelfish, including flame and coral beauty angels, are prone to nipping stony corals, and a hungry emerald crab can turn to corals too. Our list of fish that will eat your corals covers the rest.

Spacing

A scoly can swell to about twice its closed size, so measure the space from the fully inflated edge. Leave a few inches clear of that edge, and more next to corals known for long sweeper tentacles.

Growth and propagation

Scolys grow slowly and can’t be cut like other corals. Dr. Jamie Craggs, who led the first documented captive spawning in 2021, notes that fragging a single-polyp coral will likely kill it.

That doesn’t mean they can’t be propagated anymore. Ultra Coral Australia has trimmed excess skeleton off the underside of scolys for about 10 years, and new polyps grow back from the base every three to four months. Exporters now spawn them too: captive-spawned offspring reach the size of a pencil eraser in about eight months. Crowded settlement in those spawning systems produces the multi-polyp “scoly gardens” some exporters now sell.

Why are scolymia so expensive?

• Each coral is a single polyp, grown slowly and still mostly collected from the wild at depth, under quotas.
• They can’t be cut, so no two pieces are the same.
• Color drives price. Solid green is the entry point. Multicolor patterns like War Paint and Bleeding Apple cost more, and orange is rare: an orange scoly sold in Japan in 2017 for about $5,840.

Grade names like Ultra and Master aren’t an industry standard. Each seller uses them for its best color patterns. What protects you is a WYSIWYG photo of the exact coral you are buying, which is how our WYSIWYG scolys are listed.

Solid green, a War Paint pattern and red-orange. Color sets the price.

Picking a healthy scoly

• Puffy, well-inflated flesh. Reef Builders warns against a gaping mouth, which “is usually a sure sign of poor health.”
• Flesh all the way to the rim, with no bare white skeleton showing at the edge or underneath.
• No torn or peeling patches and no brown slime.
• A feeding response when food is offered.

Quick answers

Are scolymia hard to keep?

Easy to keep alive in the short term, harder to keep looking perfect for years. Stable water, low indirect flow, moderate light and regular feeding are what separate the two.

Are scolymia aggressive?

Semi-aggressive. The bigger issue is space, since a scoly swells well past its skeleton.

How big do scolymia get?

Most pieces sold run from about 1 1/4 to 5 inches across.

Do scolymia split?

Not on their own in most tanks. Multi-mouth pieces exist in the wild, and farms create new polyps by trimming the base, but a single scoly dividing in a home tank is rare.

Scoly vs. acan, acantho or trachy?

Acans, Acanthophyllia and Cynarina are in the same family as the scoly. A trachy (open brain) is in a different family altogether. Care overlaps: all of them want low placement, gentle flow and regular feeding.

Sources

• Tidal Gardens, Scolymia coral care
• Reef Builders, an introduction to Scolymia (Homophyllia australis) care (2024)
• Reef Builders, how Homophyllia australis are collected (2025)
• Reef Builders, first captive spawning of Homophyllia australis (2021) and propagating Homophyllia from the bottom up (2022)
• Reef Builders, captive-spawned scoly growth and temperature (2024)
• Scott Shiles, Reef Builders, solitary showpiece corals (2026)
• Leonard Ho, Reefs.com, Scolymia australis (2012)
• World Register of Marine Species, Homophyllia australis
• Florida Administrative Code 68B-42, marine life rule

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.