LPS, SPS, Leathers, Mushrooms and Polyps
Deciding which types of corals you would like to include in your reef aquarium can be a daunting task. Factors such as aggressiveness and needed living conditions will determine which corals and invertebrates you can include in your tank and where they must be placed. There are many different species of coral on our planet, yet they all tend to fall into one of the following categories; just click a coral type to be taken to a more detailed description.
Large Polyp Stony Corals (LPS)
This category of corals gets its name from the corals’ large, fleshy polyps and their ability to lay down a calcareous skeleton. These corals are very prevalent in the reef aquarium industry because of their hardiness and beauty. Brain, Frogspawn, Hammer, Bubble, Fox and Acanthastrea Corals all fall into this category.
LPS corals are very hardy but do require some basics to remain healthy and proliferate. These corals propagate by budding or splitting and, in the right conditions, can do so very often. To lay down a calcareous skeleton, the corals need adequate levels of available calcium. Most reef aquarium experts agree that a calcium level of 400-450ppm is ideal for LPS corals. If the calcium level in the aquarium is too low, the corals will not have enough calcium to properly form their skeletons. If the level is too high, then other essential elements can be “locked up” in the excess calcium and, thus, will not be available to the reef inhabitants.
Lighting for LPS corals should be in the medium to high range and should be a mixture of daylight bulbs (10-20k) and actinics. You should figure on using 3-7 watts per gallon of water for LPS corals. The actinics will cause the corals to phosphoresce, giving an aesthetic benefit as well as causing an increased production of zooxanthellae – the symbiotic eukaryotes which provide food for the corals via photosynthesis. Although LPS corals can be fed small pieces of fish and shrimp, it is not advised since the zooxanthellae will already be producing food for the coral; excess feeding can lead to water quality problems.
Warning: LPS corals can have sweeping tentacles that will extend at night and burn other corals if contact occurs. This burning adaptation helps the coral keep its little piece of the reef clear of competitors for the same food source, mainly light. Ergo, placement is extremely important.
Polyps and Zoanthid Corals
Zoanthids (commonly referred to as button polyps, zoos or zoas) are great for the novice reef aquarium hobbyist. These corals are very hardy and can flourish in a variety of aquarium conditions. Ranging from dull browns to electric blues, zoos make a great aesthetic addition to any aquarium. They have the desirable trait of being able top spread over large areas, covering empty spots in the tank; they have even been known to spread to equipment like power heads, overflows and other unattractive equipment.
Zoos require moderate lighting. In heavily lighted aquariums, they will need to be placed near the bottom half of the aquarium. Also important, zoos require light to moderate flow to capture food and absorb essential elements from the water. These corals use zooxanthellae for photosynthesis but will take solid food if it is present.
Propagation of zoos occurs by budding. New polyps often stay attached to the mother and, thus, form a large colony that covers whatever they are on. Zoos are an invasive species and will grow onto anything that is placed next to them, including aquarium equipment and other corals. Be attentive when placing them as you don’t want them to cover up any specimen corals you want displayed. An easy way to keep zoos from spreading everywhere is to place the colony on your sand bed. It has been observed that placing colonies on the sand bed will keep them on their original rocks as they do not like to move directly onto the sand. If you have a large colony that is spreading onto other coral, you can use a razorblade to cut the zoanthids away from the coral in question. You can then use the separated pieces as new frags. You can then trade these frags to a friend or sell them back to the local fish store (LFS).
Mushroom corals are one of the most uncomplicated corals to keep in the reef aquarium and have invariably been a staple in the beginning hobbyist. These corals have wimpy bodies and come in all colors and sizes one can imagine.
Mushroom corals do not like high-intensity lights and, thus, if you’re using metal halides, it is important to keep the mushrooms near the bottom of the tank. Most mushroom corals prefer low-flow conditions, although some will tolerate a slightly moderate flow.
These corals hold onto gravel using their feet and can drive if they determine they would like a more reasonable place in your aquarium. They do not produce a calcareous skeleton, so a steady supply of calcium is not important.
Dosing your tank with essential elements like Iodine, Strontium and Molybdenum is advised.
Mushrooms employ zooxanthellae for making food via photosynthesis, but they will take solid eats if it is present in the water. In fact, some are voracious eaters.
Propagation of these corals occurs by budding. This is a process by which the “mother” coral will produce a smaller coral, called a bud, from her foot and the coral will gradually move away from the mother to its own light source. Once it moves out from under the mother’s canopy and finds sufficient light, it will stop moving and grow into a full mushroom. Budding can happen indefinitely, and this is the reason most mushroom corals are sold as a collection of polyps attached to a rock.
A mushroom coral can be self-propagated by first cutting the coral off at the foot (Leave a small piece of foot on the rock and it will grow into a new mushroom.). With the cap of the mushroom in your hand, cut it into pieces like a pie, trying to leave some of the mouth on each piece. Then, take a tray full of rock rubble and place it in a very low-flow part of your aquarium, dropping pieces of the mushroom onto it. Over time, the pieces will attach themselves to the rubble. At that point, you can take the pieces of rubble with growing mushrooms and glue them in various places in your aquarium.
Soft coral is a category that includes the leather corals, carnation corals, chili corals, pipe organ, and Kenyan tree corals. This category of corals can be complicated to summarize as there are varying conditions in which each needs to be kept.
We’ll describe these corals in two categories; the first category contains the soft corals that use photosynthesis to create food and the second has the corals that do not.
In the photosynthetic category are the Pipe Organ and Leather corals. These corals, like the others described above, use zooxanthellae for photosynthesis and collect food and nutrients from the water. Photosynthetic soft corals require a higher flow than most as they do not use the light as effectively as LPS or SPS corals; therefore, they need to capture food and nutrients from the water to flourish. The Leather Corals need higher flow because, on occasion, they will slough their outside skin which must be carried away by the current. The Pipe Organ is unique in this category as it actually lays down a calcareous skeleton in which it protects itself. The Pipe Organ coral is very peaceful and does not have sweeper tentacles, making placement an aesthetic focus.
The non-photosynthetic category has the Carnation, Kenyan Tree and Chili corals. These corals are difficult to keep and are recommended for experienced hobbyists or those that have aquariums especially suited to the care of these corals. Non-photosynthetic soft corals do not use zooxanthellae for photosynthesis and, thus, must be fed every day to maintain health. They should be placed under overhangs and out of direct light where they have a strong flow that brings food and nutrients constantly.
Small Polyp Stony Corals (SPS)
SPS corals get their name from the small fleshy polyps that lay down a calcareous skeleton. This skeleton is the base of every reef on the planet and provides a habitat for many other species including fish, shrimp and other invertebrates. These corals use zooxanthellae in the same way that LPS and other corals do, but they require more specific conditions to grow and maintain health.
SPS corals are very sensitive when compared to other corals and require high-intensity lights (metal halides), perfect water quality and a constant supply of available calcium. Using a 10-20k metal halide bulb in conjunction with actinic T5’s or Power Compacts has proven to be a great combination for these corals. Figure on using about 7-10 watts per gallon of water for SPS corals. This is a drastic increase from the 3-6 watts per gallon for LPS coral, but the increase is necessary because of the reduced polyp size of SPS corals and the reduced amount of available zooxanthellae for photosynthesis.
Due to the reduced amount of zooxanthellae in SPS corals, it is sometimes necessary to feed the corals using phytoplankton or other coral food such as “Marine Snow.” If you are using a refugium on your aquarium, then you are probably providing daily phytoplankton, so feeding will not be necessary.
Propagation of SPS corals is accomplished by sexual reproduction as well as budding and splitting. Hobbyists will often “frag” a coral by removing a part of it and affixing it to a piece of rock. This frag will grow to become another colony over a period of time if provided the right conditions.