Public Aquariums

Most aquarists like to visit a public aquarium from time to time and once there are drawn to the marine areas. Usually the displays are excellent but not always, even the professionals can make mistakes or have mishaps.

My local public aquarium made a very basic mistake which was pointed out to them. In a large reef display they put a large number of damsel fish which looked very impressive at first. I say ‘at first’ because the numbers diminished quite rapidly. This was because they also introduced two rather large lionfish. Now, we all know what lionfish are likely to have for lunch don’t we. They did! Before all the small fish disappeared the lionfish were removed and now have their own smaller display aquarium.

Anyway, public aquariums are the place to see some excellent display aquariums in which creatures too large for a home system are kept. In addition there are often some reef systems on display which usually draw quite a few ‘oohs’.

The London public aquarium has various displays and the attached short video is one of them. At the beginning of the video is a water motion section, the movement presumably generated by some hefty timed pumps. Don’t worry about the colour, the video changes quickly.

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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 Clown Trigger Fish

Though it is regularly seen in public aquariums, this fish is not commonly kept by aquarists. It is successfully kept by a good many nonetheless.

Seeing this fish in a local fish shop or anywhere else is an experience, the shape, the colours, it is really something. Anytime I see one anywhere I spend quite some time looking.

The fish is commonly known as the clown trigger and properly called Balistoides conspicilum. Why is it called ‘trigger’? This is because of the dorsal fin, for security the fish can go into a rock crevice and raise the dorsal fin, the second spine locks it in place. To release itself the fish exerts pressure on this second spine – the trigger – freeing the locking mechanism.

These fish are not suited to a reef aquarium as they could make a meal of mobile invertebrates and maybe some sessile invertebrates as well. As a snack, if the clown trigger can catch smaller fish it could eat them too. This would really please the aquarist! In addition, the fish could decide that the carefully placed reef rocks need re-arranging, again not an action that will endear it to the aquarist. Another reason is that the fish needs a lot of swimming space and in most reef systems the reef takes up a great deal of seawater volume.

So it is clear the fish is suited to the larger fish only system. Those with small and medium aquariums should not attempt to keep the fish as it could grow to 20 inches (circa 50.75cm). Many clown trigger fish being sold in stores are small, often only 3 or 4 inches, so growth must be allowed for.  An aquarium of 100 gallons (circa 400 litres) net or larger is the size needed. This is a large system as the fish requires rocks that form caves so that it can find security, these rocks of course reduce net seawater gallonage. The rocks should be firmly positioned so that they will resist any attempted design changes. On the same theme, heaters that are in the display aquarium should have guards fitted; these are generally available and not expensive. In a fish only aquarium a sump is a definite advantage as first it provides an area where heaters can be placed out of harm’s way and secondly it increases the net gallonage of the system. It should be remembered though that when stocking is considered the seawater in the sump is ignored.

Stocking the aquarium needs care. The clown trigger is very territorial and will take exception to another trigger in their area (the aquarium!) and could do the same with other large fish. Designed for dealing with crabs and other prey with shells, the teeth of the fish give the impression that it is not for messing with. So the fish should only be kept with other large or larger very robust ones that are well able to take care of themselves. These other fish should be of a different colour and shape.

Clearly if the aquarist wishes to keep a fish only aquarium with a high number of varied fish types, the clown trigger is not a fish to choose.

When introducing fish to the aquarium for the first time the clown trigger should be the last one in, this creates the chance for all the fish to ‘accept’ each other. It is also very helpful if, on introduction, the clown trigger is smaller than all other fish present. On no account should the aquarium be overstocked.

An aquarist could introduce the fish and find that it is impeccably behaved and wonder what on earth all the cautions were about. Another aquarist could find the fish a total berserker! So it’s best to be prepared.

Feeding is easy as the fish will take just about anything on offer, though for a fish such as this brine shrimp and flake are a bit of an insult! Pieces of de-frozen fish, mussel meat, shrimp and the like are foods usually taken without problem. The fish is confident and can be fed from the fingers, but beware of those teeth, an aquarist can be forgiven for being nervous! It has been reported that hard shelled food should be given on occasion as this wears the teeth. The fish becomes quite tame and if movement is detected near the aquarium it will usually beg for food.

Over time the fish will be seen nearly all of the daytime hours in open water and becomes a real pet and a favourite. They are very hardy and long lived if attention is given to maintaining a high quality environment.

The aquarist who can provide a suitable environment for the clown trigger is lucky indeed. 

The link is to some pictures and text:

http://www.aquaticcommunity.com/marinefish/clowntriggerfish.php

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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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