Corals are marine animals classified as parasitoids. They live at shallow depths and are attached to the sea floor, forming multicolored colonies. They inhabit warm and hot coastal areas that are well-lit and oxygenated. Their wealth is enormous, so it is worth getting to know them better before implementing them into your aquarium.
Among the corals there are almost 7.5 thousand different species. Aquarists customarily divide the corals into several basic groups:
–soft – these are all corals that do not form a calcareous skeleton (Sarcophyton, Sinularia, Capnella, Zoanthus, Ricordea, etc.);
–LPS (Large Polyp Stony corals) – are hard corals with long polyps (euphyllia, plerigora, lobophyllia, etc.);
–SPS (Small Polyp Stony corals) – this group includes hard corals with small polyps (acropora, montipora, hydnopara, etc.);
–Non-photosynthesizing cor als – characterized by the lack of zooxanthellae, or symbiotic algae living in the coral tissue (Gorgonia, Menella);
–anemones (a separate group).
The above classification allows you to match corals to certain environmental requirements, although it does not fully correspond to their official systematics.
Soft corals do not form a calcareous skeleton, and their polyps are fused together by tissue. Most of them are easy to keep, so they are recommended to beginner aquarists (especially the species that have zooxanthellae). Soft corals do not require crystal clear water, strong light, circulation or super efficient filtration. Sometimes even regular water changes are enough.
Corals of the genus Sarcophyton (leathery) are the most hardy, while corals of the genus Dendronephthya are much more beautiful and delicate – and therefore more difficult to keep. They range in color from yellowish-orange to various shades of red. If we provide them with proper conditions, they will enjoy their beauty for a long time. On the other hand, aquarists that will want to tackle breeding more difficult species may reach for Zoanthuses or Ricordee.
LPS corals are much more difficult to keep than soft corals. They require clean water, supplementation (calcium, strontium, trace elements) and constant feeding (phytoplankton, plankton, zooplankton). Furthermore, the so called “pumping” of corals must also be taken into account. They repeatedly increase their size and can then “steam” other corals nearby.
LPS are more sensitive to fluctuations in water parameters and light quality. Therefore, proper circulation is very important and must be intensive but not so intensive as to jerk long coral polyps.
SPS corals are recommended for experienced aquarists, as keeping them is quite a challenge. The water must be extremely clean and keeping nutrients low requires the use of e.g. a skimmer and good quality filters. On top of that there is also a calcium reactor or refugium. There is also a lot of supplementation to be used (microelements, bacteria, nutrients, fluids for the Balling method). In addition, you need a good quality lamp with adequate power, giving enough light. All this translates into significantly higher costs of keeping an aquarium. Thus, one can conclude that small-polyped hard corals are not only the most difficult to maintain, but also the most expensive.
It is also worth mentioning that SPS corals differ significantly when it comes to requirements. The easier to keep species include montipora, seriatopora and stylophora, while the most difficult to maintain are usually acropora.
Due to the lack of zooxanthellae, these types of corals feed heterotrophically and this is the reason why they are most difficult to keep. Most of them start starving and eventually die when placed in an aquarium. Soft corals of the genera Dendronephtya and Scleronephtya belong to the most difficult ones, while Gorgonians and Dendrophylia can acclimatize much faster and stay in the aquarium for a longer period of time.
In terms of variety of forms or colors, anemones are not inferior to other corals. Among the most popular are Quadricolor and Crispa. Although many anemones have zooxanthellae, they usually require regular feeding.
Keeping a marine aquarium is therefore not an easy matter. It requires patience and persistence. Already while planning the aquarium we must decide which corals we want to keep, as this is one of the factors determining the level of difficulty. Among corals we will find species more or less demanding, and only on our aspirations depends on what challenge we will face.
Featured photo: Wikipedia