Soft corals are members of the order Alcyonacea. These corals can grow to over 2 feet across in the wild, and are found in a variety of colors. Soft corals are found mainly in tropical waters around the world in varying environments ranging from coral reefs to inter-coastal channels at depths up to 150 feet.
Soft corals will defend their space on the reef by secreting a chemical that inhibits the growth of neighboring coral. In reef aquariums, it is important to leave adequate space between different species of corals to avoid problems with growth or aggression. Most soft corals grow rapidly in reef aquariums, and are relatively hardy corals for the inexperienced reef aquarist. Soft corals have different light and water flow requirements, so should be selected based upon the environment in which they will be kept.
Soft corals will sometimes shed their protective coating within the aquarium in order to clean detritus and bacteria from their bodies. This mucus often irritates other corals and should be removed from the aquarium.
The most common form of reproduction in soft corals is asexual by budding, a process in which the parent coral produces a miniature replica of itself that eventually breaks away and attaches to a hard structure. This is common in a well-established reef aquarium that is properly maintained.
Most soft corals contain the symbiotic algae zooxanthellae within their bodies, and receive nutrients from the algae when exposed to high light levels. Members of the genus Dendronephthya do not contain zooxanthellae, and require the supplemental feeding of micro foods designed for filter-feeding invertebrates. Soft corals benefit from the addition of calcium, strontium, and iodine, along with trace elements, to promote growth and maintain the health of the specimen.