The Bubble Coral

This coral adds to all the differing shapes and colours of corals that could be added to the reef aquarium. It belongs to the stony or hard coral type.

Besides bubble coral other common names are octocoral, bladder and grape coral. The proper name is Plerogyra sinuosa. It is not difficult to obtain and if seen in a store is easily recognized, as the name implies it is covered in inflated fairly large bubbles (or bladders or grapes). On sight the coral appears to be delicate but they are fairly tough. Nevertheless, handling and placement need some care.

The coral is often roundish with the bubbles emerging from the upper surfaces. The bubbles are inflated and it is reported could expand up to around 500%, leaving the wall of the bubble the thickness of one zooxanthellae.* Quite thin then!

The coral is expanded during daylight hours. At night the bubbles retract and tentacles appear which are used for feeding.

As already said some care is needed with handling and placement. Though the coral is tougher than it looks, handling should be minimized (as with all corals) and the chosen place on the reef should not be close to sharp pointed or edged rocks in case of damage to the coral, the bubbles could rub against the adjacent rocks in seawater currents. Ensure the coral is secure; a fall could damage it and lead to infection. The coral can be placed nearly anywhere on the reef as it does not require powerful lighting, however strong lighting does not appear to cause any trouble once acclimatized. A newly purchased coral should not be immediately exposed to very powerful light as they may have been used to low light in the wild and the stronger light could shock and damage it, so it is best to keep overly powerful light off the coral anyway. Reef quality lighting (spectrum) is required because of the zooxanthellae, it could be possible that the size of the bubbles is controlled by it, the lower the lighting strength the larger the bubbles to ensure there is enough light. What does mainly limit potential position is the strength of the seawater current, this should not be strong or the bubbles will be too violently shaken or will not expand to their fullest. The best seawater current strength is low to moderate. A final point on placement – it is capable of extending quite potent sweeper tentacles which could attack and damage adjacent corals, so maintain a good space between it and any neighbours. This is good practice with corals anyway.

The coral is not overly striking in colour as some are; though the colours vary they are not bright. This is not to say the coral is not attractive, it certainly is. It could be green, ivory, cream or white and some have bubbles that have clear colourless narrow stripes on them.

This coral does not present any feeding problems; there isn’t any need for suspension feeding. A small piece of de-frosted fish or similar can be gently placed on the coral and will be taken in, what could be easier? The coral is easy to feed and sometimes is overfed because of it. One feeding every other day, or longer intervals according to experience should suffice.

The bubble coral should not present any difficulty even to a moderately experienced aquarist, provided that seawater quality is high and attention is given to proper placement on the reef with regard to seawater current strength, security and lighting. The coral is yet another variation that Mother Nature has evolved which can be an attractive and interesting addition to a reef aquarium.

(*Reference: Aquarium Corals. Eric H. Borneman)

The first link is to photographs, click on it to enlarge. The second is a short video.

http://www.poppe-images.com/images/search_results.php?keyword_mh=Plerogyra+sinuosa&x=53&y=8

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The Feather Duster Worm

Reef aquariums could be home to many life forms. One of these is the obvious, fish, in many aquariums these are small and inoffensive, and in bigger systems larger varieties could find a place. The major consideration with fish is that they are reef friendly.

Quite apart from fish there are many varieties of life. As the systems in this case are reefs the next is corals, both hard and soft. The corals are really what make the display a reef, the rocks may be ‘live’ and there may be fish flitting about, but it is the corals that make the picture.

Seen less are sponges as these are considered difficult by many aquarists and therefore they are not always attempted. It is reported that many sponges are not as difficult to keep as imagined, but their demise is often because of poor collection when damage is caused or when the sponge is allowed to come into contact with air. Algae can be another sponge enemy.

A spectacular life form that could be kept in a reef aquarium is a worm. Not just a worm though, this one is a real show off. The worm lives in a tube and is considered very attractive because of the head of feathery tentacles that appear. They are expanded into the seawater in order to trap food. The expanded tentacles do look similar to the old fashioned dust mop or feather duster that tackled cobwebs etc in days of old.

The worm is understandably commonly called the feather duster worm, or sometimes the peacock worm. The proper name for arguably the best is Sabellastarte magnifica. Feather dusters are common in warm seas and are usually easily obtained from local fish shops.

The tube extends from the rubble or rocks but all of it is not usually in sight. The tube could be up to 6 inches in length and the extended tentacle crown could be between 2 and 3 inches in diameter. The worm slowly extends the tentacles often stopping during the process and if everything seems fine the tentacles are completely extended. As they fully emerge they open up into the distinctive head.

The worm doesn’t appreciate strong seawater currents because of the head. If the current is too strong the worm could withdraw back into the tube. It is best to locate the tube in an area where only slight to moderate currents exist.

If a worm is seen to be hanging listlessly out of the tube it is likely to be dying.

When the tube with the worm within is first introduced to the aquarium the proper acclimatization technique should be applied. During this period it is best to ensure the tube is not exposed to air at all. Once the worm is ready for transfer the tube can be placed securely between rocks being careful not to crush it, when the worm is active it should adjust any faulty anchorage. Place the worm as said in an area of light to moderate currents, and lower down on the reef particularly if the lighting is powerful. The worm hasn’t any need for lighting as corals have. A worm that is positioned in bright light could be slow to appear until it is accustomed to it. It is reported that the worms do not like high temperatures – a top temperature of 76 deg F is sometimes quoted, though I kept one at 77 deg F for a long time.

Sometimes an aquarist can be alarmed as the worm drops its crown of tentacles. This could have been caused by stress produced by too high a temperature, excessive and sudden seawater currents, too large a change in seawater specific gravity or harassment. The first three are easily avoided. Harassment is avoided by ensuring that only suitable tank mates are present. Many common reef fish, such as damsels, dwarf angels etc could nibble at the worm’s tentacles. There are more that could cause a problem. Fish such as the copper-band butterfly (Chelmon rostratus) should be avoided. The best fish to keep with the tubeworm are small dottybacks, fairy baslets, gobies, blennies and the like. The worm can disappear into its tube at a terrific speed thus avoiding trouble, but repeated occurrences of this lead to stress. Once any problem has been corrected leave the worm alone. It could take a longish period to re-appear, and they are capable of re-growing a crown.

The tube worm feeds on very small plankton in the wild. In the aquarium once the worm has been given time to settle and is displaying its full crown of tentacles it can be target fed. Using a small syringe-like device, a small amount of fine filter-feeder food can be ejected ‘upstream’ and allowed to drift over the tentacles. If necessary seawater movement pumps can be temporarily turned off though this should not be necessary. It is best not to squirt the food straight at the tentacles or it is likely the worm will withdraw them believing danger is present. In an aquarium where there are many other filter feeders the food shouldn’t go to waste and the seawater quality shouldn’t be affected.

Looking at the suggested fish companions for the worm it seems the ideal home would be a nano aquarium. In these small systems it is usual to keep smaller inoffensive fish. The worm can successfully be kept in a large system subject to the other inhabitants, which means a lot of discipline could need to be applied by the aquarist.

The feather duster worm is a different and very interesting addition to a captive reef. Below is a short video.

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Large Aquarium!

Marine aquarists who have a successful system, no matter what the type, fish only or mixed reef, are mainly satisfied. A successful marine system can be stunning to see and this applies not only to aquarists who know ‘what goes on’ but to the uninitiated as well.

Big aquariums are not unusual nowadays. By big I mean really big. Most people have seen them, you know, the ones with the odd black tipped reef shark cruising about! They’re in public aquariums of course.

Home aquariums, though not on the scale as in the last paragraph, can also be big. Myself, I see ‘big’ as 6ft x 2ft x 2ft, but this size is not uncommon. Nowadays it goes considerably beyond that.

The link is to a video featuring an aquarium more than twice the length of the above. The measurements of the display aquarium are 13ft x 3ft x 2.5ft. Linked to the main aquarium are two others, a sump and a refugium. The sump measures 6ft x 5ft x 2ft, and the refugium 5ft x 1.5ft x 1.5ft. Some size system!

I’m too lazy to work out the seawater gallonage, but routine seawater change time must be quite something, somewhat more than a 5 gallon bucket!

There’s a lot of fish to be seen and some of them are quite big, however with an attached sump and refugium of those sizes the seawater quality should be high.

Many aquarists idly dream about a larger system, but the owner of this one didn’t mess about.

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Maintain And Watch

What kind of an aquarist are you? Are you a ‘hands-in’ tinkerer or a watcher, or perhaps a mixture of the two?

There’s nothing wrong with tinkering as long as it’s within reason. Constantly changing the reef for example is not going to do a lot for the security of the fish. There’s often an improvement that can be made, usually small. The early months in the life of an aquarium is when most tinkering is likely to occur.

Me, I’m a watcher. That’s not to say that I don’t tinker on occasion, but it isn’t very often. It is necessary to deal with the overgrowth of corals and the like or the display quality would begin to deteriorate because of changed and reduced seawater currents, and also the loss of light to lower corals. Normal routine maintenance often requires ‘hands-in’ for various reasons, usually powerhead intakes that have debris present.

What the living captive reef needs is stability of seawater parameters, lighting quality and time to develop. Seawater parameters are easy, routine checks confirm the situation. Lighting just needs a little maintenance and changes of bulb and/or tubes from time to time.

On the wild reef, barring storms and disasters, sometimes man-made, there isn’t any over-interference, there is stability of habitat.

My soft coral aquarium has been running for 6½ years. I do regular maintenance once weekly, so hands go in the seawater then if necessary. Apart from that the reef is left alone though it is of course monitored.

Closely looking at the visible reef rocks it can be seen that they are covered with various marine growths. On the surface is much coralline, though to be truthful there isn’t much rock surface to be seen. In addition are many, many short hard growths that look like sticks, about 1 inch long and 1/8 inch thick. At first I thought they might be small tube worms or anyway some kind of worm, but despite close observation I have not seen any evidence of any type of worm. I’ve tried reference books to no avail, also the internet. Being honest I’m not too bothered about identification as they are clearly not malignant and interesting enough.

On the underside of rocks when viewed at night (it seems easier to see them then) are lots of tiny tubeworms. This time they are clearly tubeworms as the tiny feathery heads can be seen, not the same shape as the big showy ones but a small fan about ½ inch or so in diameter, usually considerably smaller. I find these tube worms in my canister filter as well, during maintenance I do my best to protect them but a good few meet their doom.

When cleaning the canister filter I always have to rescue tiny shrimps, about ½ an inch long. They usually float on the seawater surface apparently trapped by the meniscus. I return them unharmed to the display aquarium, avoiding the attention of the fish. If the shrimps in the canister filter sink they are lost, I can’t retrieve them. There are growths that appear in the canister filter that are repeatedly destroyed during maintenance, though they re-appear. I have been unable to identify them.

I have one worm that lives at the top of the reef. It was not there when the aquarium started but appeared a year or so later, or that’s when I noticed the small tube anyway. The tube is now around 2 inches long maybe a little more, and around 3/8 of an inch in diameter. It is definitely a worm as it can be seen at the mouth of the tube, though it doesn’t come out. It is not a feather duster. What it does to feed itself is trail a sticky thin thread in the seawater current, when food becomes attached to the thread it winds it in and consumes it. At feeding time when brine or mysis shrimp are on the menu the thread looks like one of those commercial fisherman’s long hooked lines with a good catch. I’ve again been unable to determine what the worm properly is, so it’s called ‘Fisherworm’. Very technical!

Things appear in areas of the aquarium where they are not expected. Button polyps appeared well down the reef, not put there by me. I have ‘transplanted’ the odd few button polyps and they have developed into healthy groups. A coral or two appears out of the rocks, sometimes they thrive but often they disappear again. Strange creatures wander about mainly noticed at night; one in particular looks like a leading candidate for an alien movie. I’ve no idea what it properly is. There isn’t any damage on the reef in any part so it isn’t one of those unwanted pests.

One of the most beautiful appearances is a calcareous type alga that’s growing on the glass quite high up. Fortunately it’s not one of the viewing glasses that I clean. It is a whitish growth that is very similar to snowflakes joined together. The first time I noticed it the size was about ½ inch or so across, which increased to around 2 inches. Then it fell off and disintegrated. However, I note that it is back and growing, this time it is a little lower down and, hopefully, will remain attached.

There are many life forms that use my captive reef as home. I introduced the fish and major corals. Others have just appeared. Well, ‘just appeared’ cannot be correct can it!

When I set up the aquarium I didn’t use any live rock at all, but inert porous rock. Over a lengthy period this rock has become live, permitting me to close down the canister filter used for bio-filtration (I still run it but there isn’t any bio-media inside, it’s purely for surface agitation and additional seawater). The inert rock was interspaced with rocks attached to purchased corals. It is these coral rocks that must have been the entrance avenue for the life that has appeared. Coral rock is live rock after all.

So, I’m a watcher. Things appear and disappear, grow slowly or quickly. Little life forms scurry about, fish cruise quietly always ready for more food, corals sway in the currents, ‘dawn’ and ‘dusk’ come and go. I try and leave it alone.

Diminutive as it is, it’s a real living reef.

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The Pulse Coral

The pulse coral belongs to the soft corals and is well known. It is often seen in local fish shops and though often at a higher price than many other soft corals, is not out of the reach of most aquarists.

These corals are attractive in general, but the main attraction is the pulsing of the polyps, they rhythmically open and close. There has been considerable argument over why this should be, and the most obvious answer held sway for quite a long time. This answer was that by pulsing the coral drew suspended food particles to it so that they could be captured. Watching the coral’s action this seems reasonable. However, the latest thinking that I am aware of is that the pulsing is to obtain more oxygen, in other words a breathing movement, more seawater is passed across the polyps thus more oxygen becomes available. Some aquarists automatically dismiss this as it is compared to the similarity of human breathing. Several authorities support the ‘breathing’ reason. I am not able to state the scientifically proven correct answer. Perhaps there will be scientific enquiry into the coral and facts will emerge. If they already have I’d be pleased to know.

Anyway, the attractive coral is upgraded to fascinating by the pulsing of the polyps. Sometimes in an aquarium the polyps cease to pulse, or only pulse weakly. Again, at least to me a definitive answer as to why this should be is not known. There has been argument, some saying that in an aquarium iodine is likely to be lacking and this causes it. However, some have measured for iodine and found it present at a correct level yet there isn’t any pulsing. Others have suggested that the aquarium may have saturation levels of oxygen and there isn’t a need for pulsing. The latter one could have some merit if the coral’s reason for pulsing is related to oxygen. (The respiration reason for pulsing is cited in some respected books.) Another reason suggested is that there is excessive nitrate in the seawater. If the polyps reduce their pulsing action nitrate is easily checked for, but unfortunately there doesn’t seem to have been any feedback from aquarists on this point (to my knowledge).  Again perhaps science will come to our aid one day. The good thing is that even if the pulsing does reduce or cease, the coral does not seem to decline and remains attractive.

Pulse coral is the major common name, Xenia elongata or Xenia umbellata the proper ones (two separate types). There are other pulsing corals. They are suitable of course for a reef aquarium. The coral has a thick ‘trunk’ which leads to many ‘branches’, which in turn split off and lead to many polyps. The coral attaches to rock. It is important that the coral receives sufficient light as the flesh contains zooxanthellae which supply the majority of the coral’s food requirements. Ensure the light reaching the coral is direct and bright. Seawater movement should be moderate. Excessive seawater movement will have a detrimental effect.

The pulse corals are not difficult to keep and do well in an aquarium, provided of course that seawater quality is high and lighting is adequate. Placement seems to be one key to success (as with many other types), this could be a little problematic as placing the coral higher up the reef should provide sufficient light but perhaps too much seawater movement. When placed, watch the coral, does it expand properly and does the expanded coral look comfortable, that is not banging about in the current? It is easy to see when things are fine.

Having a pulse coral in the aquarium certainly adds to interest to state the least. If the pulsing action reduces or ceases, first be sure there isn’t excessive seawater movement. Then check for nitrate, if the level has increased reduce it by increasing the amount of routine seawater changes, at least temporarily. Investigate the reason for the nitrate increase and correct it. (The guideline for nitrate in a reef aquarium is 10ppm or less.) As a final check, all else having proved not to be the reason, check the seawater oxygen level, perhaps the seawater is carrying the maximum? Overall though, this coral should give little trouble.

The link below will give further information and photographs, just scroll down the page, lower down is a picture of a coral in action.

http://reefkeeping.com/issues/2004-02/ac/feature/index.php

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Take A Tour

Coral reefs are fascinating places with a massive diversity of life. These reefs are the foundation of an aquarist’s interest, it is the reefs that supplies most of the livestock, and from which all of it originated.

Some aquarists maintain a mixed reef, probably the most prevalent of aquarium systems. There also those who wish to keep their captive reef so pristine with absolutely perfect corals, or perhaps very difficult to keep corals, that fish have no place in them at all – these are coral only systems. Others keep fish only aquariums with the advantage that fish can be kept which are not reef friendly, such as many butterfly fish which would be likely to make a meal of corals. Yet others keep seahorses that need to be on their own as they cannot compete with fish for available food. Some keep shrimps only, perhaps Mantis that are not welcome in a ‘standard’ system, or groups of cleaner shrimps and similar.

Whatever system is kept the aquarist usually has a general fascination with the wild reefs. Some are very fortunate and visit them, many snorkeling over them with the occasional short dive a few feet down. Others are trained divers using scuba equipment; they can get much deeper and see the reefs in more detail.

Even if not divers ourselves, we can take advantage of some scuba divers skills with photography. Scuba divers visit many reefs in many parts of the world and so there are records available of the varied reefs.

No matter what the aquarist’s interest is there are usually photographs available with fish, big or small, and corals of many types.

Try the link and tour a few of these reefs. There are wreck pictures too though these are not as interesting to aquarists. The link opens the Red Sea page. Click on a photo to enlarge it.

http://www.scubatravel.co.uk/photored.html

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The Staghorn Coral

These corals belong to the hard type and are much used in reef aquariums. Writing a text on them in general terms is the only way given the space available.

They are given their common name because, obviously enough, the branches of the coral generally resemble the horns of a stag, though the branches vary considerably. There are other common names such as tabletop coral and cat’s paw coral (some have flat tops as does a table so there are also those that resemble a cat’s paw), but these names do not fit so well overall and are not as widely used. The proper name for the type being looked at here is Acropora. I can immediately find 47 types of Acropora in the references available to me and I’m sure there are many more, one suggests a total of 300 or more. They each have their own proper name under the heading of Acropora, hence the general look only.

As a hard coral they belong in a reef aquarium of course. The aquarium should have powerful lighting such as metal halides, probably best supplemented by, say, two actinic fluorescent tubes. High seawater quality is a must, and the calcium and alkalinity levels need to be monitored. Acropora corals demand calcium and the amount of usage can be surprising in a well stocked reef, so supplementation from commercial sources could be possible in a small system, but it is likely to be too expensive and cumbersome for a medium or large one. In the latter the usual practice is to install a calcium reactor. The calcium level is best kept between 420ppm (parts per million) and 450ppm, though some aquarists elevate this to around 480ppm. Such a high level is not really necessary as long as the suggested lower levels are maintained. Alkalinity in an aquarium is best if it is higher than natural seawater levels. Alkalinity resists the tendency for pH to drop because of acidic action, in other words it acts as a buffer. The best level in an aquarium is between 3.5 meq/L and 4.5 meq/L. 4.0 meq/L seems reasonable. Some fluctuation doesn’t matter provided it is fairly minor. (NB. meq/L can be converted to dKH if desired, multiply by 2.8.)

So the corals need high quality seawater with appropriate calcium content and alkalinity, plus correct lighting. The lighting could have an effect on the coral’s colour; the colour could change from that when purchased. This change is usually because the symbiotic algae, the zooxanthellae, are reacting to the lighting available.

Another requirement is seawater movement. The majority of the corals are used to high seawater movement and this should be duplicated as far as possible. A minimum flow rate suggested by the guideline is twenty times the display aquarium net gallonage per hour, which is double that suggested for a soft coral display. This flow can be provided in the usual ways such as powerheads. It is worth considering the high output types with wide delivery nozzles as opposed to narrow nozzle types, particularly the ones that can be controlled and made to alternate seawater output level. Whatever type is chosen, they need to be positioned so that a jet of seawater is not directed straight at a coral, though this isn’t as important with wide nozzle types.

Not all Acropora corals require high seawater movement, though as said the majority available to the marine aquarist do. One way of generally judging seawater flow requirements is to consider the colouration, if it is bright then it is likely that intense light is required which brings the coral closer to the surface where strong movement prevails. Another indicator is the length and shape of the branches, if they are short and club like they resist high seawater movement better; longer and more slender branches are more likely to break. Generally, if there are any doubts place them in an area of high movement and, as with all introductions to the captive reef, observe to ensure all is well.

Acropora corals could worry the aquarist when they are first placed in the aquarium. Even though the conditions for them are excellent, they could take a while to settle before commencing to grow. Once they have settled however, and provided conditions are maintained, they shouldn’t be a problem.

When placing the corals allow room for growth, if conditions are good they are fast growers, some more than others and this growth can be such that the reef becomes overcrowded fairly quickly. Having said that, the corals are excellent for ‘fragging’, a term used in the marine hobby for culturing additional corals from a mother colony. This practice is excellent for the hobby and for the wild reef: for the hobby ‘fragged’ corals appear to be more resilient than those from the wild, for the wild reef if corals are ‘fragged’ not so many are required to be collected. Therefore if the captive reef does start to become overcrowded ‘fragging’ is a definite action to consider, and it isn’t difficult.

Though it varies, the branches of the corals are fairly fragile and snap easily, more so towards the tips. Therefore care is required when they are handled. Sometimes they can be positioned so that rocks hold them until they establish themselves, but it is probably better to secure them with some aquarium epoxy putty, which sets very quickly.

Acropora come in all sorts of shapes and colours. Most seem to be branched and resemble a terrestrial bush to some extent, with generally uniform branches sprouting out and upwards. These branches could, as said, be thick, short and club like or longer, dividing and slender. Others grow to a flat top shape thus the name ‘table coral’. The pink and blue of some types are, to me anyway, particularly lovely, though the colours vary with many others.

These corals are more demanding than most, but not all, of the soft corals and the aquarist has to be sure that he/she is willing to provide the ‘extras’ required – seawater should be top notch anyway, with very low nitrate and phosphate. The extras are controlled levels of calcium and alkalinity, high seawater movement and sufficiently powerful lighting. A stable environment is required as generally the corals tolerate changes poorly.

The link gives many pictures of the corals. Click on a picture to enlarge.

http://www.poppe-images.com/images/search_results.php?keyword_mh=Acropora&x=40&y=9

If the aquarist can provide the environment for the corals, the reward is a colourful and very ‘reefy’ display. A successful hard coral reef display is regarded by some as the pinnacle of achievement.

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