A Saltwater Reef Aquarium is not complete without a reef, meaning corals. Corals can be easily maintained or extremely difficult to care for and grow, and different corals have different requirements. However, there are many requirements common to most corals including: proper lighting, water movement, and stable water parameters. Corals are cultivated three different ways: mariculture, aquaculture, and wild grown. Maricultured corals are those cultivated in an enclosed section of the ocean or a raceway filled with seawater. Aquacultured coral is coral that has been grown in a completely controlled environment such as a home aquarium. Wild grown coral is that which has been cut from a reef in the ocean, imported, and then sold. When I purchase coral, I like to always try to purchase aquacultured coral, as it has a much higher survival rate in your aquarium. Additionally, one is not supporting the pillaging of what few natural reefs still remain on Earth. In this article I will explain the informal classification of coral categories within the hobby. This is not a scientific categorization. Pictured is a common mariculture farm.
In the Saltwater hobby soft corals are corals that do not have a calcareous skeleton but are made up of “soft” flesh. The soft coral group includes: zoanthids, palythoas, and sinularias, just to name a few. Soft corals do not require strict water parameters, can thrive in low water movement, and usually grow quickly. They are recommended for beginners in the hobby and tend to be favorites with them as well. Soft corals are also very easy to propagate, but most are extremely poisonous to humans. Safety protection must be worn when propagating most soft corals . The Neon Toadstool pictured below is a favorite among all hobbyists.
LPS (large-polyped scleractinian or large-polyped stony) corals have a calcareous skeleton and as you can probably guess, a large polyp and soft flesh covering its skeleton. These corals require more stable water parameters than soft corals because LPS corals use calcium, carbonate, magnesite, and strontianite from the water column to build their skeletons. LPS corals also have stinging tentacles that are used to capture prey or ward off adversaries. They are photosynthetic, meaning that they make food from light, so they need the proper lighting when kept in an aquarium. LPS corals can come in very extravagant colors and are always fun to feed. Pictured below is a one of a kind Rainbow Acanthophyllia.
SPS (small-polyped scleractinian or small-polyped stony) corals are mainly calcareous skeleton and have very little soft flesh. These corals are also photosynthetic, require very stable water parameters, and usually medium to high water movement. SPS corals use the same elements from the water column to build their skeletons as LPS corals but usually consume a greater amount at a faster rate. Most SPS corals require adequate distance from other corals as well because they also have stinging tentacles that can kill other corals if they come in contact. These corals not only thrive on light, elements, and minerals from the water column but also dissolved organic matter and zooplankton. SPS can be extremely expensive and have very elaborate color patterns. The Jaw Dropper Acropora pictured below can easily sell over $1,000.00. There are some corals that are just not meant to be owned.
NPS (non-photosynthetic) corals do not use light at all as a source of energy. Instead, these corals rely on feedings to thrive and grow. NPS corals ingest phytoplankton, zooplankton, and nutrients from the water column. Some of these corals have a calcareous skeleton, and some do not. Water parameters must be stringently maintained for NPS corals to grow and thrive. Most of these corals are considered to be extremely difficult to keep in the home aquarium, mainly because they require feedings multiple times a week. Though NPS do not use light, they express quite the color scheme, and most are very unique. A good example is the Sun Coral in the picture.
There’s nothing like taking a small fragment of a coral and growing it into a large colony. It is very rewarding and certainly gives one a feeling of accomplishment. Growing coral is, by far, my favorite part of the hobby. Remember that this is a hobbyist’s categorization of these coral groups, so there are many corals that will fall into a gray area or have characteristics of more than one category. All corals require stability rather than the perfect water parameters. There is no need to chase numbers, but rather one should keep the numbers they have close to those of the ocean and its water parameters. And keep them constant. In the saltwater aquarium hobby one is not really caring for the animals and corals, but they are really caring for the water. Always research a coral of interest before purchase so that you may see if your lifestyle is compatible with the care and attention that coral requires. Happy Reefing!
By Josh Kirkland