Sinularia flexibilis

Common Names: Flexible leather coral, finger leather coral, flowing finger coral

Phylum: Cnidaria

Class: Anthozoa

Order: Alcyonacea

Family: Alcyoniidae

Range: Widespread throughout the eastern Indian Ocean and western Pacific

Natural Environment: While this photosynthetic soft coral with long, flowing lobes can be found in a variety of different environmental areas, it is most often seen inhabiting fairly shallow areas where somewhat strong currents exist.

Water Requirements: Calcium 380 to 430 mg/l, alkalinity 2.5 to 3.0 meq/l, pH 8.1 to 8.2, specific gravity 1.024 to 1.026, phosphate < .015 mg/l, nitrate < 15 mg/l, and a temperature range of 74 to 83°F (23 to 28°C).

Captive Care

This hardy soft coral is quite common both in the wild and in the trade. Though it can tolerate a wide array of environmental conditions, it tends to do better in brightly lit areas, either from metal halides or fluorescents, and where moderate to strong water movement exists. No direct feeding is required because they are photosynthetic, but like all photosynthetic corals they do feed on plankton and will do better if you provide invert foods, either by supplementation or by keeping live sand and/or a refugium that produces zooplankton.

Aquarium Placement

Placement in the aquarium can be wherever conditions favor it, but keep in mind that it can grow quite large quickly and may therefore shade out nearby specimens sooner than anticipated. Provide enough space between them and their neighbors. These are especially good corals for those new to the hobby, as they are as hardy as mushroom corals.


Sinularia flexibilis produces terpenes called flexibilide and dihydroflexibilide (sinularin and dihydrosinularin). These chemicals are known to be toxic to other reef species, such as Acropora, Catalaphyllia, Euphyllia, Plerogyra, and Porites (Borneman, 2001).In fact, this species has had many incidents recorded in which it has appeared to inhibit or stunt the growth of various stony corals.

A Recommended Coral

Since it’s a hardy and readily available soft coral that is nice looking and usually inexpensive, I still recommend it for the reef aquarium. However, it is important to keep activated carbon that is properly maintained running at all times in order to safely remove any terpenes produced.


As for those wanting to propagate this species by fragmentation, I recommend doing it outside the confines of the aquarium and allowing the frags and mother colony to heal in a quarantine system before any portions are returned to the show aquarium.

In the Trade

This species is also a good shipper; healthy specimens are frequently available in the trade. Besides being quite hardy, it’s also disease resistant and an excellent choice for the beginning reef aquarist so long as activated carbon is used.