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; 52 medium · 17 difficult
Temperament: 58 peaceful; 51 mostly peaceful · 6 aggressive

115 species

Soft corals first

Soft corals are where nearly everyone starts, and the catalog agrees: the mushrooms, zoanthids, green star polyps, pulsing xenia, Kenya tree and the leathers are the rows rated beginner or easy. They have no hard skeleton, so they shrug off the alkalinity swings that kill stony corals, they take moderate light, and most of them grow fast enough that you will be trading 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 euphyllias and the brains also throw sweeper tentacles after dark that sting whatever sits within a few inches, which is why a new frag goes in with a hand's width of empty rock around it.

SPS, the branching corals that demand stability

Acropora, montipora, birdsnest, stylophora and pocillopora make up the small-polyp stonies, and these are most of the rows rated difficult. They need strong light, strong random flow and water chemistry that does not move between one test and the next. Birdsnest, cauliflower coral and the plating montiporas are the gentler introductions. 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 most of the sea fans carry no algae in their tissue, so light does nothing for them and every polyp has to be fed with food. That means target feeding several times a week at the least, and for dendronephthya near-constant plankton. They are some of the most colorful animals on this page and among the hardest to keep alive, which the difficult ratings reflect.

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 and favites, the plate corals and the giant cup mushroom reach out at night with tentacles or a mouth that digests neighbors. 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?

The rows rated beginner: mushroom corals, zoanthids and palythoa, green star polyps, Kenya tree, clavularia and anthelia, the leathers, bubble coral, the cactus coral and other pavonas, and the meteor shower coral. All of them tolerate the swings of a new tank better than any stony coral.

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 and the sea fans have no algae and starve without regular target feeding.

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. Leave a hand's width between frags, 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.

Index