by Peter Cunningham of Aquarists Online

Live Aquarium Corals: There are numerous reasons why people are drawn to the saltwater aquarium hobby.

Whilst there are many, two of the more popular ones are color and movement.

The color and movement of the life which creates interest within the aquarium hobby are primarily fish and live aquarium corals as these are the ones which the ‘beginner aquarists’ normally sees first either in books, on the internet or in their local fish shop.

Anemone at New England Aquariums

There are also many other forms of life which the newcomer will see on their travels such as invertebrates, anenomes, snails, sponges etc however the fish and/or corals will normally be the ones which cause the potential new aquarist to become a new aquarist.

Urchin and Snail

When making the decision to start a new saltwater aquarium, or any aquarium for that matter it is important to do as much research as is required to allow the life which is in your care the best chance in life.

In this article I hope to assist in your research by discussing live aquarium corals.

If the decision is made to keep corals in the aquarium instead of having a fish only aquarium then there are more areas which you need to understand/appreciate.

Of course fish can also be kept in an aquarium where corals are housed. Before it is detailed what extras you may need to understand it is important to understand the different types of corals and how they are classified.

Corals are normally classified by the home aquarist into three separate areas.

  • These are soft corals,
  • long polyp stony corals (LPS), and
  • short polyp stony corals (SPS)

In scientific terms the classification of corals is a huge subject matter and an entire book could be created just to cover this subject alone.

For the beginner it is important to understand the live aquarium corals general classification – more important is to understand the corals requirements.

Sun Cup

All of the coral is important but probably one of the most important parts is the polyp.

Coral polyps come in all shapes and sizes, some are individual and some are colonial.

The polyp is a very hard working area of the coral.

A coral polyp is a very simple organism however it is the area of the coral which does the feeding, lays down calcium carbonate, defence, removal of debris etc.

It receives a lot of its energy from single cell algae called zooxanthellae.

Zooxanthellae exist in the majority of corals and allow corals to thrive and grow even in nutrient starved conditions like the home aquarium. Basically the zooxanthellae provide the coral polyps with energy which allows them to do their job.

The relationship between the coral and the zooxanthellae is what can only be called symbiotic. Both parties benefit from this relationship. The zooxanthellae provides the polyp with energy using photosynthesis and the coral provides the zooxanthellae with protection.

Zooxanthellae can exist in open water however, even though they are exceptionally small in size they are still at risk from predation.

This is not the case when they exist within the tissue of the coral.

Live aquarium corals which do contain zooxanthellae are termed as being symbiotic and corals which do not contain zooxanthellae are classified as non-photosynthetic.

The structures that are created by corals can be very diverse however this is defined by the type of coral.

For example soft corals do not have a hard calcium carbonate base rather they are more tissue based therefore quite often the structures soft corals create are more ‘wavy’.

Pink Carnation Coral

Basically they grow upwards towards the light but also spread out sideways in order to catch more light. These types of corals move silently but with finesse when in the water currents.

Hard corals on the other hand are very skeletal based with a tissue covering it. This tissue which contains the polyps ‘lives’ on top of the skeletal base and when the polyp lays down more calcium carbonate the coral is able to grow.

The structures created by hard corals is very vast and varies from species to species – some corals spread outwards and create a structure which is very plate light, others create structure which are very much like trees, others create structure which are very dense like hedges.

The requirements of the live aquarium coral in your home is exceptionally important as it is with anything else which is placed in the aquarium. Live Aquarium corals are very sensitive creatures, much more so than fish and therefore their individual requirements need to be fully understood before even considering purchasing one.

Related Article:
Coral Requirements

by Peter Cunningham of Aquarists Online

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