Aquarium corals

Corals are the centerpiece of a reef tank, from beginner soft corals to demanding SPS. Each profile lists the light and flow a coral wants and how difficult it is to keep.

Tank size: 11–53 gal; 11 gal (40 L) to 53 gal (200 L); half the list needs 20 gal (75 L) or more
Temperature: 75–81°F; 24–27°C, most of the list
pH: 8.1–8.4; Most of the list
Difficulty: 46 easy; 54 medium · 15 difficult
Temperament: 58 peaceful; 51 mostly peaceful · 6 aggressive

115 species

Soft corals first

Soft corals are where nearly everyone starts, and they make up 29 of the 46 corals marked beginner or easy. The other 17 are stony corals, among them the seven pavonas, the bubble and pearl bubble corals and the meteor shower coral. Most mushrooms and zoanthids are marked beginner or easy, and so are the green star polyps, pulsing xenia, Kenya tree and the leathers. The elephant ear mushroom and the Yuma ricordea are marked medium, and the gold polyps are marked difficult. Soft corals have no hard skeleton, so they shrug off the alkalinity swings that kill stony corals. They take moderate light, and most grow fast enough to trade frags within a year. Xenia and green star polyps spread over anything they touch, so give them an island of rock they can have to themselves. And palythoa and some zoanthids carry palytoxin, so wear gloves when you frag them and never boil a rock to clean it.

LPS, the big-polyp stonies

Hammers, frogspawns and torches, duncans, candy canes, acans and blastos, the brain corals and the plate corals all build a skeleton under fleshy polyps that swell during the day. Most of the catalog's LPS rows sit at medium difficulty. They want stable calcium and alkalinity more than they want intense light, and they feed on meaty food at night if you offer it. The hammer, frogspawn, torch and elegance corals have stinging tentacles that reach several inches. A frogspawn's night sweepers can reach 6 to 8 inches. Give each of them about 6 inches (15 cm) of empty rock. The favia and favites brains throw sweepers too and want 4 to 6 inches. The lobed brain coral digests neighbors with filaments instead and wants 6 inches or more.

SPS, the branching corals that demand stability

Acropora, montipora, birdsnest, stylophora and pocillopora make up the small-polyp stonies, and they account for six of the 15 corals marked difficult. They need strong light, strong random flow and water chemistry that does not move between one test and the next. Cauliflower coral, birdsnest and the plating, undata and encrusting montiporas are the gentler introductions, marked medium. The acroporas want a tank that has already run a year without drama. Every one of them turns brown or white within days when something slips, which is the point of the difficulty rating.

Corals that have to be fed

Sun corals, dendronephthya, scleronephthya, the gold polyps and the yellow mopsella, tangerine and red swiftia sea fans carry no algae in their tissue. Light does nothing for them, so every polyp has to be fed with food. That means target feeding at least daily for most of them, and near-constant plankton for dendronephthya and scleronephthya. They are some of the most colorful animals on this page and among the hardest to keep alive, which the difficult ratings reflect. The pink and purple sea fans and the sea fan gorgonian carry algae and live on light instead.

The aggressive ones and how far apart to put them

A handful of rows are marked aggressive, and it is not a temperament in the fish sense. Galaxea, the favias, the favites and the giant cup mushroom reach out at night with tentacles or a mouth that digests neighbors. The plate coral and the long-tentacle plate coral are marked aggressive too. The mobile plate coral and the slipper coral are marked mostly peaceful, but they still sting. Amplexidiscus, the giant cup mushroom, closes on small fish and shrimp that rest on it. Place these low and alone, downstream of nothing you care about, and move anything that starts to recede at the edge nearest them.

By the numbers

Smallest

Largest

Easiest to keep

Fits a 20 gallon tank

Fits a 30 gallon tank

FAQ

Common questions

What are the easiest corals for a beginner?

Most mushrooms, the zoanthid button polyps and palythoa, green star polyps, encrusting star polyps, clavularia and anthelia are marked beginner. The Kenya tree and broccoli tree corals are marked beginner too. The colt coral is the one leather marked beginner, and the other leathers are marked easy, as is the Florida ricordea. The Yuma ricordea and the elephant ear mushroom are marked medium, and the gold polyps difficult. Bubble coral, pearl bubble coral, the pavonas, meteor shower coral, sunset coral and the Turbinaria cup coral are the stony corals marked beginner. The soft corals among them handle the swings of a new tank better than most stony corals.

What is the difference between soft corals, LPS and SPS?

Soft corals have no skeleton and bend with the flow. LPS (large polyp stony) corals build a skeleton under big fleshy polyps, hammers and brains for example. SPS (small polyp stony) corals are the branching and plating acroporas and montiporas with tiny polyps, and they are the most demanding.

Do corals need to be fed?

Most carry algae that feed them from light, and they get by on that plus what drifts past. LPS corals grow faster when fed meaty food at night. Sun corals, dendronephthya, scleronephthya, the gold polyps and the chili coral have no algae and starve without regular target feeding. The yellow mopsella, tangerine and red swiftia sea fans have no algae either. The pink and purple sea fans and the sea fan gorgonian carry algae and live mostly on light, with occasional fine plankton feedings.

How much light do corals need?

It depends on the group. Soft corals and most LPS are happy in moderate light and will bleach under too much. The SPS corals want strong light. Each profile describes what the coral in question wants, and a new coral always goes in lower than its final spot.

Why do corals sting each other?

Many corals defend space with sweeper tentacles at night and with chemicals in the water. A hand's width between frags works for the milder corals. The euphyllias, elegance coral, lobed brain coral, chalice coral, Pectinia coral and velvet horn coral want about 6 inches (15 cm) or more. None of them is marked aggressive. Keep the aggressive corals low and apart, and run carbon to soak up the chemical warfare.

What water conditions do corals need?

Nearly every profile here lists 75–81°F (24–27°C) and a pH of 8.1 to 8.4. For stony corals, alkalinity, calcium and magnesium matter as much as temperature, and stability matters more than any single number.

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