Sebae Anemone

The sebae anemone is recognized by its tough, leathery column covered with small bumps on the outside and its long, thin, pointed tentacles numbering in the hundreds. Its natural colors are tan, cream and brown; the tentacle tips are often slightly purple or pink. In the aquarium the tentacle crown reaches 20–30 cm. It was long known as Heteractis crispa and was moved to the genus Radianthus in a 2019 revision.

In the wild it hosts many species such as Clark's, pink skunk and saddleback clownfish; in the aquarium it is sometimes accepted by ocellaris and percula as well. But it is a noticeably more difficult species than the bubble tip anemone. Dyed specimen warning: bright yellow or neon-colored sebae anemones are usually individuals that have bleached and then been dyed; the dye blocks light and the anemone eventually starves to death. Pure white individuals may also have bleached during shipping. Choose individuals with natural color, a closed mouth and plump tentacles. Specimens in the trade are wild-collected.

It lives in the sandy and rubble areas of reefs from the Red Sea and East Africa to the Central Pacific. It attaches its foot to a hard surface beneath the sand or in a rock crevice; often only the tentacle crown is visible.

• Volume: at least 200 liters and a mature, stable reef aquarium at least 6–12 months old.
• Water: salinity 1.024–1.026 specific gravity, pH 8.1–8.4, temperature 24–27°C; nitrate and phosphate should be low.
• Light and flow: strong reef lighting and moderate flow. Provide at least 10 cm of sand and pieces of rock under the sand where it can attach its foot.
• Pump protection: it may get sucked into pumps while roaming; all intakes should be covered with sponges.
• Reef compatibility: Reef-safe with caution; when it moves, it stings the corals it touches.
• Acclimation and medication: Acclimate by the drip method for at least 1 hour; copper-based medications are lethal.

Carnivorous. The nutrition from its symbiotic algae is not enough; give small morsels such as mysis, chopped shrimp or mussel 2–3 times a week. For bleached or newly bought individuals, regular feeding with small morsels determines survival.

It may wander until it finds a suitable spot. Once settled it usually stays put; shrinking at night and opening in the morning is normal. Its tentacles sting and can catch small fish and shrimp that fall near it.

Good companions: Clark's, pink skunk, saddleback, ocellaris and percula clownfish; peaceful reef-safe fish; sexy shrimp.

Avoid: butterflyfish and angelfish that pick at anemones; anemones of other species; corals placed near it.

Start the aquarium with a single individual. Unlike the bubble tip anemone, it is not known to reproduce by splitting in the aquarium; each individual needs its own space.

In the wild the sexes are separate; it releases eggs and sperm into the water. There are rare records of it spawning in the aquarium, but no offspring are obtained.

• Bleaching: loss of color is the loss of its symbiotic algae; it can recover with strong but gradually increased light and regular feeding.
• Signs of decline: not opening for days, a gaping mouth, a torn column or a bad smell.
• Death: a dead anemone rots quickly; it must be removed immediately and a large water change done.

Cannot be told apart externally.