Life Span Of Tropical Marine Fish

We look after our fish very well, don’t we. Whether it is a fish only aquarium or reef aquarium, a lot of thought goes into choice, taking into account compatibility, size and character. All in all, the fish should be healthy and happy.

The marine aquarium is a stable environment (or should be) with all the parameters at their proper levels. The fish receive a varied and appropriate diet. There is little stress I would imagine, apart from the odd squabble that usually doesn’t amount to much. Predation doesn’t exist.

On the wild reef the fish are more stressed as they hunt for food, attempt to avoid becoming food, maybe defend a territory, ensure they have a safe haven for the night and additionally have the need to breed.

Disease is a threat in both environments, but more so in the aquarium. The aquarium gallonage is really miniscule compared to the enormous gallonage of the reef, so the appearance of disease is much more serious. Just consider the entry of oodinium. The fish in the wild may meet it once or twice or not at all. If it does appear it is unlikely to cause a problem. So disease is an area where captive fish could be more stressed than their wild counterparts.

So the lifespan of fish that are commonly kept in captivity is easy to record. All that is required is for the aquarist to note the date when the fish arrived at his/her aquarium. My fish have dates recorded - for example, the flame angel (Centropyge loricula) is 5¾ years old. This excludes the period in transit and with the retailer of course.

Knowing the real age of a fish is close to impossible. How long has the fish been in the wild? Who knows, maybe there is a size related calculation that could assist? But size relates to diet and overall health to a considerable degree.

Perhaps a comparison could be made between wild and captive fish. The fish selected would have to be of the same type and of the same size. So taking the flame angel, it is easy to note the date the fish entered an aquarium, but the fish in the wild would have to be tagged or similar, and how would track of it be kept? No, it isn’t going to happen.

So the only lifespan that could be measured would be of fish in an aquarium. That would not reflect the potential real lifespan, of course, as there are many variables and a lot of the variables have changed.

An inquisitive aquarist keeping fish in captivity will just have to refer to a record and state to a fellow aquarist with pride ‘I’ve had this fish for x years.’

---

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

Tags: aquarium, aquarium-fish, marine-aquarium, marine-fish, reef-fish, saltwater-aquarium

The Banggai Cardinal

The Banggai Cardinal, proper name Pterapogon kauderni, is a relatively new fish for the salt water aquarium. The fish in the aquarium is fairly sedentary, but has lovely colouring with black vertical striping on a silver body. The tail is long and forked, again being silver/black. It has become popular and can now be seen in many home aquariums.

I became concerned about this lovely fish as I thought there was a danger that supplies of the fish from the wild would dry up. Then I learned something potentially much more serious - perhaps wild stocks were in jeopardy which made my initial feeling insignificant.

As far as supplies drying up, this isn’t going to happen. First, the fish in captivity is much more helpful than many marine species in that it brings its young into the world much like a freshwater cichlid - it is a mouth brooder. Eventually the young require a defence and this is easily supplied with real sea urchins, the long spine types, or something artificial which is similar and quite easy to accomplish. So some pressure on wild stock is eased a little in that way. Only a little though, as the fish can only produce a few young in each batch. Clownfish, for example, produce far more young. But at least breeding is an option.

The second concern about wild stocks being in jeopardy as said is much more serious. It is estimated (on what basis I don’t know) that circa 700,000 of these fish is collected for the aquarium trade every year. The total population is thought to be in the region of 2,000,000. It doesn’t need a mathematician to work out that the collection ratio is high. The fish come from one small area in the Pacific Ocean and therefore is not widespread.

A proposition had been put to CITES to ban totally the collection of this fish, on the basis that the population could not be sustained with such a high collection ratio. This ban would mean that US and EU imports would cease, though presumably captive breeding would mean the fish would remain available but at a very much increased price.

However, in deliberations CITES have not imposed a ban. This is because the government of the area has agreed to a strict management programme which is to include training of local collectors and the number of fish that can be collected in view of the estimated populations. The aquatic trade is involved, and monitoring is to be carried out by an independent authority. CITES has accepted the fish is at risk, but, as said, have not banned collection.

This is good for the marine hobby. The fish will still be imported, but in smaller numbers, and the number available to the hobby boosted by commercial and private breeding programmes. The local collectors still have their income, or part of it, protected as far as possible. Above all, it appears a commonsense outcome in this day and age when there are many pressures, sometimes misinformed, to ban ‘exploitation’ of the wild.

---

Tags: aquarium, aquarium-fish, Coral Reef, marine-aquarium, marine-fish, reef-fish

Clownfish Anemones

The term ‘clownfish anemone’ is an incorrect description, but it describes them well enough. These are the anemones that clownfish use as a home. Probably nearly everyone, aquarist or not, has seen the amazing sight of an unharmed clownfish within the stinging tentacles.

Some of these anemones are in fact called the Carpet Anemone (Stichodactyla gigantea), the Pink Anemone (Heteractis malu), the Bulb Anemone (Entacmaea quadricolor), and Ritteri Anemone (Heteractis magnifica). There are others.

The anemone is more likely to settle well into an aged aquarium. In other words, a system that has been running for quite a few months as this normally means that it is stable. The bio-filtration has settled down and the rock structures have a population of some algae and tiny life. I know of one retailer who will not sell one of these anemones to an aquarist unless his/her system is at least 9 months old.

There are other points to note. The first is the often repeated one - water quality must be high. It should also be noted that lighting needs to be correct as the anemones contain symbiotic algae (zooxanthellae). In a reef aquarium this is normally not a problem as the corals have the same requirement, but in a fish only system (provided the water quality is high enough) the lighting might need alteration.

When purchasing an anemone be sure that there aren’t any signs of damage, particularly on the foot. Sometimes there is damage in that area as getting the anemone off its rock is very difficult. It is much better if there is a rock attached. It is a good idea that when the anemone has been chosen at the retailers, research the natural colour. If the anemone is not this colour, but pale white (unless its meant to be white) or translucent, don’t buy it.

Also these anemones can grow large. I had one which completely outgrew my aquarium and I had to sadly let it go complete with clownfish (I couldn’t bear to separate them). Research will indicate the chosen anemone’s potential size.

Make sure pump intakes and overflows are guarded. If the anemone does wander as it might (see below) it could get sucked into a pump or overflow and be badly damaged.

Placement in the aquarium is very important. If the anemone is not happy with its position it is likely to wander until it is. Much to the irritation of the aquarist it may decide the perfect spot is on the front viewing glass, or somewhere else that is inappropriate.

The anemone should be placed fairly high on the reef, even on the top. The foot should go in a hole or crevice, as the anemone should be happy with that from a defensive point of view - they can contract into it, at least to an extent for protection. If there is a rock attached already to the anemone, don’t try to take it off. The anemone’s grip is very strong and damage to the foot is likely. Just make a hole for the rock to go into, leaving a suitable crevice or such above as described. If there isn’t a rock attached, the anemone should be placed into a crevice etc and given time to attach. To facilitate this circulation pumps may need to be turned off for a few hours (not the bio-filters if these are pump driven). The anemone should attach quite quickly - much more rapidly than a coral.

So the anemone is in place and has adequate lighting. There is one more requirement, and that is water movement. The surface of the anemone should be disturbed by random water movement (that is, not continuously one-directional). The flow need not be powerful, but moderately so. This can be judged by the tentacles when the anemone is expanded, they should wave about like flowers in a moderate breeze.

It seems anemones are fussy. Perhaps they are, but once settled they will give little trouble if water and lighting quality are maintained.

Feeding couldn’t be more simple. It is reported that the anemones can survive but not grow and multiply from the products of the zooxanthellae only, they need additional food. They are well equipped for this, as they have stings in the tentacles (nematocysts) which are fired into the prey when stimulated and poison is delivered. The food can be a small part of a frozen fish etc, the normal aquarium food used for feeding other livestock. The food should be cut fairly small, defrosted (not in a microwave, use seawater or R/O water) and placed in the tentacles. The anemone will move it to the mouth. If there is a resident clownfish it may well steal the food, even though it is too big for the fish to eat. In this case, place the food as close as possible to the mouth of the anemone and ensure the tentacles take hold. Recalling my clownfish, it would even do its best to pull the food out from the anemone’s mouth. It was always interested in the anemone’s food, even though it had been purposely fed beforehand. Don’t overfeed the anemone, once or twice a week should suffice.

Clownfish will not always take up residence in an anemone, much to the aquarist’s disappointment. Some aquarists declare that this is because they are tank bred, and do not recognise the anemone. I don’t dispute this, but what of the young in the wild, they have no formal education that ’this is an anemone’ but find one nevertheless. In addition, tank bred clownfish are known to adopt an anemone, it has been reported often. Perhaps it is instinct.

I would suggest that failure to adopt an anemone could be because it may be the wrong type of anemone. It is known that different clownfish favour different anemones. In view of this I have added a link at the end of the text so that a check can be made.

Bear in mind when considering an anemone that they are equipped to catch prey. The fish in the aquarium are prey for the most part as far as the anemone is concerned. This could occur when a fish swims close to the anemone and gets ‘blown’ in by the water currents. I recall having my heart in my mouth a good few times at how close some fish ventured, but fortunately a mishap never occurred.

An anemone, particularly if it has an attendant clownfish or two, is a really interesting addition to the aquarium. They need good husbandry and they could get large!

http://www.fishlore.com/clownfishanemonechart.htm

---

Tags: anemone, aquarium, aquarium-fish, aquarium-livestock, marine-fish, reef-fish

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.

---

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.

I’ve Heard Of The Cleaner Shrimp But What Is The Cleaner Fish?

I would imagine that all marine aquarists have heard of, and probably seen, the cleaner shrimp (Lysmata amboinensis). This colourful shrimp is very popular, becoming used to the aquarist very quickly and even walking around on the hand if the opportunity presents itself - a large and strangely shaped fish to be cleaned perhaps.

There is another creature known for the natural cleaning activities it undertakes. This is the cleaner wrasse (Labroides dimidiatus). The fish is commonly known as the cleaner wrasse or blue streak wrasse. There are other reef fish that undertake cleaning duties particularly when juvenile, but this wrasse does it as a full time job.

The wrasse likes to go into a small hole or crevice for security when night arrives. During the day, it seldom moves far from the area, as it is a cleaning station. In other words, the little wrasse, usually in a group, wait for other fish to come so that they can be cleared of parasites and other irritants. The wrasse goes busily about the fish being cleaned, as this is the food source. They will even enter the mouths and gills of bigger fish, including predators - the larger fish normally hang still, fins spread when being cleaned, and keep their mouths open to allow easy access. The cleaner wrasse are protected from predation during this activity possibly by their swimming motion, colours, shape, or all three. The cleaner stations are well known to other reef inhabitants, and it is known for fish to wait and queue patiently for attention. There are always enough fish for cleaning, and thus food for the wrasse.

As with many wrasse, the cleaner is hardy in a good aquarium environment. It needs plenty of swimming space and places to hide. The normal caution should be exercised with regard to health when purchasing one.

On the wild reef there are plenty of fish to be cleaned, but not so in the aquarium. Even in a fish only system where there are normally more fish per gallon, there is insufficient natural food. It follows that this will be the same in a reef system. Also of course, the last thing the aquarist wants is parasites in the aquarium. Talking of parasites, it might be thought that the wrasse could be of use in a fight against marine white spot or velvet. Unfortunately, this is reportedly not the case and the wrasse is vulnerable to the parasites as well.

When considering introducing a cleaner wrasse to the aquarium, the usual compatibility question applies, though this is not usually a problem from the wrasse‘s point of view. When the wrasse is in the aquarium, natural instincts continue. It may ‘think’ that the fish in the area are waiting for cleaning and attempt to carry out this task. These attempts can continue over and over again, day after day, and other fish can be highly irritated by the attention. The wrasse may be repeatedly warned off, though it is unlikely to be attacked, though if the system is a fish only with predators there could be a problem. Some predators, such as lionfish, may not have very good manners! It is said that if the wrasse ‘learns’ when food is available and responds to it with the other fish, the cleaning drive could diminish, as the driving force, hunger, is reduced.

As with other fish it is a good idea to ask a retailer to put a little food in the aquarium and watch the response of the wrasse. Many wrasse are easy to feed, generally being gluttons, and the cleaner type is reported to feed well too. There have been reports of starved cleaners that perished, but this does not appear to be the norm.

The food fed needs to have a little resemblance to that in the wild. Fortunately, most other fish will take it as well. Try frozen foods that are prepared for marines, such as mysis shrimp, artemia, shellfish, squid, lobster eggs and the like. Some may need to be chopped so that the cleaner can handle them. It is reported that the fish will often take flake food. A diet with plenty of variety, plus flake if possible, should be successful. Fed carefully, the seawater conditions should not deteriorate as other fish present will eat the same diet.

On the wild reef mimicry is not unknown, and so it is with the cleaner wrasse. Other fish trust the wrasse and do not hesitate to present themselves for cleaning. Taking advantage of this is a fish which is closely coloured and patterned. This is the false cleaner (Aspidontus taeniatus), which in fact is a blenny. What it does is present itself to a fish which is ready for cleaning, but instead of being useful it quickly bites a bit of fin or scale and dashes off. Not the way to win fishy friends! It is unlikely to be obtained in mistake for a proper cleaner, but the two are easily identifiable, the proper cleaner has a mouth at the front of the fish, the false one has an underslung mouth.

There are other cleaner wrasse, but none are reported to take to aquarium food as readily (I’d better avoid the word ‘easily‘) as the one discussed.

---

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

If A Fish Dies Should You Remove It From The Aquarium?

The loss of a fish is a very sad occasion and often, whether the cause is known or not, the aquarist will wonder if it was his/her fault. Most (all?) aquarists lose a fish occasionally when the rest are perfectly healthy.

Despite the sadness, the aquarist needs to take action to maintain the quality conditions inside the aquarium, which will protect other livestock from further problems. A rotting fish may cause a rise in the load on the bio-filter, and the bio-filter may not be able to cope.

The answer is yes, the fish should be removed if possible. Easy enough maybe, unless there are many rocks in the aquarium. Fish often have a tendency, probably a defence mechanism, to hide in rocks when there is a problem.

In a fish only system using an external filter and not a lot of rock, or even one which uses a good quantity of live rock, as there aren’t any corals it should be practical to move rocks about until the corpse is discovered. This will stress the remaining fish and therefore the rock movement should be minimised as far as possible by moving rocks and replacing them in a methodical manner until the corpse is found.. This should also preserve the layout of the rocks. On the other hand, the ‘fish only with live rock’ aquarist if necessary could leave the fish in the rocks and proceed as in the reef system below.

In a reef system it is more difficult. The reef is constructed of many rocks and is usually covered in may corals of various types. The aquarist is not going to be particularly keen on dismantling the reef, even if it can be done methodically. The disruption is greater, and the stress to the living fish would probably be more severe. So what is the procedure?

It is the water quality that is being watched. As said, the presence of a rotting corpse can stretch or overload a bio-filter. The reef aquarist could make the decision to ignore the dead fish and monitor the water quality. This is an option because in the reef system there are normally less fish, again to protect water quality (though the bio filtration mechanism will still have adapted to the load it has to deal with). What is being daily tested for is any presence of ammonia. At the same time, the actions of the fish should be watched to ensure they are not showing any sign of discomfort, such as increased breathing rates and/or erratic and unusual swimming. The corals too should remain as normal. If any problem does appear then the action is a water change to dilute the toxin, the amount depending on the severity of the problem.

That said, it is possible that the reef aquarist will not note any detrimental changes in water quality, particularly in a mature reef. This is because the many tiny occupants of the reef are always ready for a meal, and are perfectly able to dispose of a corpse. I have, over the years, lost fish and removed them from fish only systems, and left them alone in a reef. The reef life dealt with the problem and removal of the fish in the fish only system prevented any problem arising.

The loss of a fish calls for water quality checks, unless the aquarist is sure of the cause.
If the fish can be removed, it is best to remove it. If not, monitoring the water quality for say at least a week should provide an adequate safeguard.

---

Tags: captive-fish, marine-aquarium, marine-fish, saltwater-aquarium, saltwater-fish

Next Page »