TankBud

St. Thomas mushroom

Rhodactis osculifera

Also known as Rhodactis sanctithomae, Discosoma sanctithomae, Warty Corallimorph

SaltwaterCoral

St. Thomas mushroom (Rhodactis osculifera)

Care at a glance

Temperature
75–81°F
24–27°C
pH
8.1–8.4
Adult size
3.9 in
10 cm
Minimum tank
11 gal
40 L
Temperament
Peaceful
Social behavior
Solitary
Swim level
Bottom
Diet
Photosynthetic
Difficulty
Beginner
Breeding
Medium
Rarity
Common
Reef safe
Reef safe
Family
Discosomidae
Origin
Caribbean

Overview

The St. Thomas mushroom is a Caribbean corallimorph and an easy coral for a first reef tank.

Did you know

The St. Thomas mushroom's disc is covered in rounded, bubble-like vesicles rather than the fine fuzz of Pacific hairy mushrooms. They get it mistaken for a small bubble tip anemone often enough that some Caribbean suppliers sell it under exactly that comparison.

Caring for the St. Thomas mushroom

Give a St. Thomas mushroom moderate light, around 75 to 150 PAR, with gentle to moderate indirect flow. Place it low on the rockwork or on rubble, where it can attach and spread.

Keep it in a tank of at least 11 gal (40 L). Hold the water at 75 to 81°F (24 to 27°C) with a pH of 8.1 to 8.4. It relies mainly on zooxanthellae, and it also takes small meaty particles that settle on its disc.

It is low sting and safe near most neighbors. It multiplies in the tank by splitting, and occasional feedings of small meaty foods speed that up. A spreading patch will slowly claim rock, so give it its own zone.

Good to know

Rhodactis osculifera is a corallimorph in the family Discosomidae, a soft bodied relative of stony corals with no skeleton. The trade and field guides called it Rhodactis sanctithomae or Discosoma sanctithomae for decades. Both names are now treated as synonyms of the older Rhodactis osculifera. Pieces come in reds, greens and blues, often with an iridescent sheen.

In the wild

The St. Thomas mushroom lives on shallow rock and rubble across the Caribbean, the Bahamas and Florida. It grows as single polyps in some spots and carpets a patch of reef in others. It favors calm, slightly shaded spots over bright, exposed rock.

Common questions

What size tank does a St. Thomas mushroom need?

A St. Thomas mushroom needs at least 11 gal (40 L).

What temperature and pH does a St. Thomas mushroom need?

A St. Thomas mushroom is comfortable at 75–81°F (24–27°C) with a pH of 8.1–8.4.

What does a St. Thomas mushroom eat?

A St. Thomas mushroom relies mainly on zooxanthellae for its energy. It also takes small meaty particles that settle on its disc, and it accepts occasional feedings of small meaty foods.

How big does a St. Thomas mushroom get?

An adult St. Thomas mushroom reaches about 3.9 in (10 cm).

How does a St. Thomas mushroom breed?

A St. Thomas mushroom multiplies in the tank by splitting. Occasional feedings of small meaty foods speed up the splitting.

Related species