Two Corals To Avoid

When an aquarium is ready for coral stocking, or is up and running and additional coral stocking is being contemplated, a trip is usually taken to the local retailer to decide on what to purchase. On arrival, more often than not there is a large range of corals on display of both the hard and soft varieties, though the latter may be in higher numbers.

The choice can be bewildering. What to choose? It is said over and over again that research into potential stock before purchase is very important. Inappropriate corals are still purchased though. Many, maybe most aquarists do it. I did.

The corals look so splendid, but there are some that stand out. There are others that really stand out, and it is with these that the aquarist is overcome. So they are bought.

The first is a soft coral. Soft corals are supposed to be ‘easier,’ and so they are generally. There are always exceptions, and this is one of them.

The coral is commonly known under several names- carnation coral, tree coral, strawberry coral and cauliflower coral being some. The proper name is Dendronephthya. There are perhaps 250 different  types under this banner. They are really colourful, coming in purple, red, yellow, white, green, pink and orange. Without doubt they are beautiful - attractive is to do them an injustice. I feel quite certain that they will sell quite easily simply because of their visual appeal.

So what is the problem? Most corals help the aquarist by having symbiotic algae (zooxanthellae), which, with adequate light, greatly assists in the maintenance of the coral by providing food and ridding the corals of waste. Dendronephthya do not have this algae. They obtain food by capturing it. To survive a high level of phytoplankton and possibly zooplankton are required. This means, in a closed system, a great danger of pollution. Also the corals require fairly strong currents to bring the food to them which may not suite some other corals. On introduction to the aquarium, some do not even re-expand. Even if they do they are likely to perish quite quickly. As said, if sufficient food is provided it is likely that the tank will be polluted and then more than this coral will be negatively affected. The only good thing about the coral (apart from its beauty) is that in nature they are found in areas of very low light and also, but less, in areas of sunlight. Therefore it may be that they can tolerate many positions in the aquarium. However, be that true or not, they are not going to survive anyway.

The second coral that requires a mention is for the same reasons - difficulty of maintenance. This coral is possibly even more attractive than the one already mentioned. This is the one that I purchased (once) years ago.

In this case the coral is commonly known as the flowerpot coral or daisy coral. The proper name is Goniopora, and they are hard corals. They can be brown, green, cream, pink or yellow. Their beauty comes not only from the colour but also from the long stems of the polyps, hence the common names. These do look like flowers in a vase, and they sway in the currents in a really attractive way. They can easily be the centrepiece of any aquarium.

They are often sold as a round ball like rock, with the coral covering most of the upper and uncovered surface of the rock. The ’skin’ of the coral seems to be stretched tight over the surface of the rock and this is the first danger. The aquarist can unwittingly damage the coral when putting it into the aquarium if the support rocks are sharp, or there is insufficient support and the coral falls. Great care needs to be taken when handling these corals and their placement pre-checked.

They prefer low to moderate currents because of the long polyp stems, and also bright light. So in an aquarium lit by fluorescent tubes the coral needs to be placed high on the reef.

The second problem is with feeding. It is reported that Goniopora cannot survive on their zooxanthellae, therefore supplementary feeding with phytoplankton is said to be required. So the same problem can occur as with the first coral if due care isn’t exercised - pollution.

Even if all apparent requirements are being met it is likely that the coral will fail. It may last a month or longer, but the high probability is it will die. This happens slowly, the first indication being that the polyps, or some of them, are not expanding as much as they used to. Eventually, the polyps hardly expand at all, and more and more fail to open.

Some aquarists keep Goniopora for a ’long’ period (’long’ in terms of the expected captive lifespan of this coral) which could be 6 months to a year. In my case it was about 8 months. My coral didn’t die because of failure of the polyps, though they were quite short and, if I recall correctly, some didn’t expand at all and some polyps didn’t open, it died after a fall from the rockwork. There wasn’t any obvious damage, but the coral  became covered in a jelly-like substance and that was it.

Very advanced aquarists who may wish to experiment with the captive care of the two mentioned corals could be of great benefit to all of us. Experiments with feeding, water currents and light could be undertaken.

For the rest of us, the corals should not be purchased, and the magnet of their undeniable beauty resisted. As far as I am aware they are not threatened in the wild, but surely it is wrong to sell or buy corals that are very nearly 100% certain to die. Better to leave them to survive with nature until the secrets of keeping them in good health in captivity are known.

---

If you're new here, you may want to subscribe to our RSS feed. Thanks for visiting!

Tags: coral, home-aquarium, marine reef, marine-aquarium, reef-tank, saltwater-aquarium

Zooxanthellae

The first thing that needs to be done after writing the above is to ensure the spelling is correct. It is a strange word to us ordinary mortals, but came into being with marine biologists.

In the marine world one of the most fascinating double acts to watch is that of a clownfish and an anemone. The clown swims to the anemone and gains protection from the stinging tentacles, and, though there is argument, the anemone may gain by the clown chasing off unwanted threats to the anemone or dropping bits of food on it. To my knowledge anyway the anemone’s advantage is not fully clear.

The above example illustrates how two different life forms can be of use to one another. There is another that is much more common in marine aquariums. This one is the relationship between corals and zooxanthellae. Zooaxanthellae are in fact single celled algae that live within the tissue of a coral, often called symbiotic algae. Why should this be?

It is thought that the coral uses the oxygen and carbohydrates manufactured by the zooxanthellae. In turn, the zooxanthellae utilise coral waste products and assist in obtaining trace elements from the seawater. It is theorised that up to 90% of the corals required food may be supplied by the zooxanthellae.

For the algae light is very important, as it is required for the photosynthesis process. This is why reef aquariums are brightly lit, some with T5 fluorescent tubes and others with metal halide bulbs. Power output and spectrum need to be correct (power output for the depth of the aquarium). It is thought that the ‘actinic’ fluorescent tube is very beneficial to the zooxanthellae.

A clue as to whether a coral has zooxanthellae or not is in the colour. Generally, it is likely that corals coloured yellow, purple, red, and orange do not have the algae, and corals coloured blue, beige, brown and green do.

Both soft and hard corals may have zooxanthellae. In addition, there are others, such as the aforementioned anemones and clams such as Tridacna.

Problems can arise with this strange relationship but this is not the text to discuss that. Provided the aquarist provides adequate lighting and water quality, then all should be well.

(Reference: Marine Invertebrates. Martin Haywood and Sue Wells)

---

No tag for this post.

Have You Considered Artificial Corals?

Let’s face it not every beginner to this hobby has the courage to keep corals straight away. There are some people who are happy to keep a fish only aquarium and why not they are beautiful things.

A lot of people as said would love to keep corals with fish but are worried that they do not have the experience, knowledge etc to care for and maintain corals in a closed aquarium system.

I take my hat off to these people to be fair. If anybody is not confident enough about keeping corals then should they keep them at this time. They could learning along the way but would there be any deaths - maybe not but maybe so.

There is another option.

Artificial corals. These have become very popular of late and a lot of public aquariums are using these in their show aquariums. I have to be honest and say that I have never had them but have seen them in person both in an aquarium and in a shop.

I have to say that I was pleasantly surprised as to how realistic these corals are. There are some artifical hard corals which are of course hard and there are even anenomes which will blow around in the currents. Looking at them there is a vast arrays of colours to choose from and to be fair a very large selection.

So if you are not yet confident about keeping corals then why not have a look at them - they could be what you are looking for in the interim. Even if you have a fish only aquarium then why not take a look they might look good in your aquarium.

Plus your fish may get a shock when they go for a nibble!

---

Tags: Coral Reef, Corals, marine-aquarium, reef-tank, saltwater-aquarium

My Toadstool Coral, Is It Rotting?

The toadstool coral or mushroom leather coral, (Sarcophyton sp), are hardy and very decorative. They can grow to quite a size but this varies and is not usually a problem. These corals are suitable for a new aquarist, and, with some experience under the belt, are easy to propagate by cutting. More advanced aquarists who are ‘into’ soft corals often have a toadstool in their collection.

As the name implies, they look a little like a toadstool, but often have convolutions on the head. The usual open state is that they are expanded and many polyps extend from the upper surface of the head. If there is a clownfish in the aquarium, they will sometimes adopt a toadstool coral as home, nestling in among the polyps, which doesn’t seem to harm or bother the coral.

Sarcophyton sp. close down in the same way as other corals. They deflate and have their polyps withdrawn. Sometimes the polyps are only partially extended, and sometimes diffferent areas are not extended at all, giving a clumpy effect.

The question arose because a toadstool that had been healthy had closed up for a while. The coral had closed down normally, had opened the next day but with less polyps extended, the next with even less, and the next with none. When open it was noticed that the coral had discoloured patches on the surface of the head, and these areas had a waxy appearance. The coral stayed closed for a day or two, then began opening in reverse sequence, more and more polyps extending as time passed. Surface skin was sloughing off in the water current. This skin, not large in area, did not seem to affect any other coral. The discoloured areas disappeared and the polyps became fully extended and all present once again.

The coral was not rotting as the aquarist had feared. It was simply getting rid of surface skin. Presumably this is a possible routine occurrence on this species of coral, perhaps a means of ejecting any unwelcome passengers such as algae, accumulated dirt or even parasites.

A coral that is behaving in a different manner to normal needs observation over time. Some soft corals can stay closed for a week or more, then inflate and be as beautiful as ever.

If the period of closure seems just too long, and rot does seem to be a problem, then the coral can be carefully checked - rotting should be apparent if the area is gently squeezed with the fingers as it will tend to be excessively squashy and may break up (generally touching corals should be minimized, not touching at all in normal circumstances). Rotten parts can be cut away with a sharp pair of scissors or a suitable knife, cutting slightly into the good flesh to ensure all rot is removed. All things being equal the remarkable regenerative power of the coral will come into play.

---

Tags: aquarium, coral, home-aquarium, marine-aquarium, saltwater-aquarium

Coral Problems

Anyone sitting down with a good gardening book can be taken aback by the number of problems that could be met by any particular plant. Some are hardier and more resistant to disease than others. This is of course true for all life forms.

The marine hobby world, be it a fish only aquarium or reef aquarium, is no exception. The fish can fall to disease, and so can corals.

This is not intended to be a cover-all for aquarium coral problems. The subject would be far too large. However, an attempt will be made to consider perhaps the more likely troubles.

To avoid as far as possible any problems arising in the first place, there are four areas that need attention.
[Read more]

Tags: aquarium-coral, coral, home-aquarium, marine-aquarium, saltwater-aquarium

Good Starter Corals For The Beginner

When starting a new reef tank, especially if you are a beginner to the hobby as I am sure you may by now appreciate there is at times quite a lot to learn.

Starting a reef aquarium is only as hard as you allow it to be. Why learn all about advanced water chemistry for example at the very beginning - learn the basics first, get your aquarium running and then carry on reading, studying and learning.

Why make starting an aquarium harder by including corals in your aquarium where you have to learn a lot about how to care for and maintain them. There are some corals which are exceptionally hard to care for so why not keep some of the easier to keep corals whilst you are learning the basics and as you learn more and your aquarium ages then you can add more. [Read more]

Tags: aquarium-coral, coral, saltwater-aquarium-setup, saltwater-coral, starting-a-saltwater-aquarium

A ‘Dying’ Soft Coral

I have a soft coral (well, there we go, lucky person, actually many aquarists have got several). Seriously, I have a soft coral that’s a joy to behold.

I’m not exactly sure what it is, I believe it could come under the general term ‘colt’ coral. More specifically, it may well be Alcyonium sp. I cannot be sure. It is a multi-branched very feathery (my wife says fluffy) coral. It is beautiful. [Read more]

No tag for this post.