The White Spot Hermit Crab

Crabs are not always welcome in the marine aquarium. Some of them could cause trouble, either blundering about and knocking things over, possibly interfering directly with corals or just growing too large.

There are some crabs however that often find favour with aquarists, and these are the hermits. They are quite comical as they wander about the aquarium, and at the same time are useful as scavengers. They can be colourful too, though this is usually the legs as this is the part that can be seen. The shell is not the crab’s own; it has been found empty or taken over from a snail for example. The crab keeps itself secure in its shell with a tenacious grip. If excessive force is used to remove the crab, then the grip will not be broken, but the crab’s body will break apart. The grip is so strong because remaining in the shell means survival, outside of it means death as the crab is highly vulnerable. The crab holds itself inside the shell with its rear pair of legs which slant forward to increase strength, and in addition the abdomen is shaped to fit the shell reasonably.

This is one danger from the hermit crabs, their need for a shell. I once had a large snail and a hermit crab in the same 4ft aquarium and for a while all went well. However, the hermit began following the snail about, trying to get at its flesh and generally upset it. Eventually it damaged the snail which died. The hermit crab was next seen in the snail’s shell. Though I couldn’t be sure, I wondered if I was at fault, perhaps the hermit had grown and needed a larger home. I would suggest that a small selection of suitable shells is left in the aquarium, so that hermit crabs can change home if they have a need.

There are several suitable hermit crabs for the aquarium, and provided there are no dangers present (such as for example puffer fish) a fish only system could be used, though there needs to be rocky structures present. The best habitat however is a reef system, where the crab can find security and its ‘cleaning’ activities are perhaps the most useful.

The hermit crab being focused on here is commonly called the white spot hermit crab, or the scarlet hermit crab, or the knobby hermit crab. There may be more common names demonstrating that for identification purposes the proper name is the best. In this case the proper name is Dardanus megistos.

http://decapoda.free.fr/illustration.php?n=5&sp=225

It is necessary with this crab for the reef to be securely built, though this generally applies to all hermits, particularly the larger ones. They are not particularly naturally destructive, but just clumsy. They could grow to around 4″ (circa 10cm) including and dependant on the shell they inhabit. Only one should really be kept or it is likely fights will occur. It is also necessary to exclude shrimps in general as the crab could eat them. The hermit crab should be seen during the ‘lights-on’ period but is also active at night. They are hardy in a good habitat.

Feeding is simple as the hermit crab appears forever hungry, constantly looking for food. They will take de-frozen lance fish, mussel flesh, crab meat, and almost anything else that is edible. Hence they are fairly good at cleaning up.

This particular hermit crab is not suitable for a small aquarium; one of around 4ft (circa 122cm) should be fine. Though the crab population should be restricted to one, an aquarium of this size affords space for other inhabitants to spread interest.

This is one species of hermit crab which is interesting and colourful. However, if the aquarist wishes to keep more than one, or keep one in a smaller aquarium, there are types that could be available. For example, there is the red reef hermit crab, proper name Paguristes cadenati. This could grow to around 1½” (circa 4cm). A trip to the local fish shop (LFS) is likely to turn up hermit crabs that are suitable for the aquarist’s particular system.

With proper attention to the habitat and some to other livestock, the hermit crabs are as said useful, interesting, amusing and hardy. Additionally they pose no problems with feeding. All they require is a new home occasionally.

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The Dancing Shrimp

There are a few shrimps which find favour with aquarists; some of them have been the subject of other texts on this website. This is another favourite, both for its colouring and character.

Before starting, a picture is needed:

http://fr.reeflex.net/tiere/1019_Rhynchocinetes_uritai.htm

This shrimp comes under a few common names which could lead to confusion: dancing shrimp, rosy dancing shrimp, camel back shrimp and common dancing shrimp being some of them. The proper name is Rhynchocinetes uritai.

They’re lovely to look at and one of the common names – ‘camel back shrimp’ – refers to the clear hump on the back. Another common name – ‘dancing shrimp’ – refers to the jerky way in which they move.

The shrimp is social and can be kept in a group. They do not usually have any trouble with other commonly kept shrimp except perhaps the boxing shrimps, Stenopus sp. Obviously the number kept depends on the size of the aquarium – two could be kept in a relatively small system.

The best habitat for the shrimp is a reef aquarium as this affords all the crevices and caves that are needed. There shouldn’t be any other livestock that could threaten the shrimp of course. Keeping the shrimp in a reef aquarium does have a potential drawback though, and that is the shrimp could ‘have a go’ at soft corals, including colonial anemones. Then again, many aquarists do not have this problem. Hard coral types are usually left alone.

There is another possible advantage to having these shrimps. Please note the word ‘possible’. This concerns that unloved nuisance of many aquarists aiptasia. These anemones are often introduced on the rock of a new coral, or with live rock. After a time during which the anemones spread, an ongoing battle usually takes place between the aquarist and the anemones. This battle usually ends with the aquarist being in control generally but having to periodically re-attack. An uneasy truce could describe it. There have been anecdotal reports on the internet that these shrimps attack aiptasia, mainly young ones. It has also been reported just as often (to my knowledge) that the shrimp ignore the anemones! I haven’t seen any reports following controlled experiments. Perhaps they will, perhaps they won’t.

Generally the shrimps are more timid than other commonly kept types and avoid the bright light of a reef system, initially anyway. They should settle down and be seen more often, though they usually retain their preference for dimmer light. It is more unlikely that they will rise to take food so the aquarist may have to target feed the shrimp. This is not difficult, not least because they will take the usual fare such as de-frozen lance fish, mussel etc. They may well chase brine and mysis shrimp that have been released as food.

As with other shrimps they will shed their exoskeleton from time to time. This is to permit growth. A new exoskeleton will harden over a fairly short period and the old one looks like a shrimp albeit a dead one.

All shrimps need careful acclimatization to the new home aquarium and it is reported that this one is perhaps more sensitive. Therefore transfer to the new seawater should be completed with care. Empty out half of the seawater in the transport container. Then, using an air tube and air tube clamp, drip aquarium seawater into the container until it reaches the previous level. The drip rate is a little short of a slow continuous trickle. It is probably worthwhile carrying out this procedure twice. When the shrimp is introduced to the aquarium it must not be exposed to air. It is also worthwhile switching off the main lights for a day – this period will not harm any corals.

The dancing shrimp in the proper habitat is a delight. They will probably not be seen as often as other types. For those aquarists who battle the troublesome aiptasia wouldn’t it be great if all the anemones disappeared. No guarantee though.

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The Blood Shrimp

This shrimp is in the same family as other cleaner shrimps such as Lysmata amboinensis and Lysmata grabhami. It has more than the one common name blood shrimp; others are fire shrimp and scarlet cleaner shrimp. The proper name is Lysmata debelius.

This small shrimp will probably grow no larger than around 1¼” (circa 3cm). As the common names suggest, its body is a lovely red to scarlet. There are a few white dots on the body and the antennae are red at the base but white over the remaining length. The legs are similar. It is a real beauty. Here’s a picture:

http://commons.wikimedia.org/wiki/Image:Lysmata_debelius.JPG

As can be seen, if this little shrimp is seen in a retail shop the temptation to purchase could be high. However, as with other shrimps, there are one or two cautions or requirements.

The home aquarium should be a captive reef with high quality seawater. The shrimp is reef safe. They are suitable for a small aquarium and, small or large obviously there shouldn’t be any livestock present that could be a threat to the shrimp. They are quite social so can be kept as a pair or more. In a high quality habitat they are quite hardy.

It is important to introduce the shrimp to its new home carefully. A good way of doing this is to use a length of air line and an air line clamp. Empty half of the transport seawater out of the container then allow aquarium seawater to drip slowly in. The drip rate is short of a slow continuous trickle. When the seawater has reached its previous level some aquarists remove half again and repeat the process. When the shrimp is placed in the display aquarium it should not be exposed to air.

It is likely the shrimp will disappear for a good while, perhaps some days. Once more settled it should appear and become bolder. It will most likely not be as bold as other cleaner shrimps, and may or may not rise for food. The shrimp does not require bright lighting but should become accustomed to it as time passes.

Feeding is straightforward as the shrimp will take directly offered de-frozen foods such as small pieces of lance fish, mussel and similar. They may chase other free floating foods such as brine and mysis shrimp, and will even try to catch flake. If the shrimp remains a little timid and does not rise for the food only appearing lower down, then target feeding is easily accomplished.

As with other shrimps the blood shrimp will molt. This is when the shrimp discards its exoskeleton for a new one to permit growth. The new exoskeleton takes a while to harden and the shrimp normally hides during this period as it is at its most vulnerable. The aquarist shouldn’t be immediately alarmed if a replica of the shrimp is seen – it may be thought the shrimp is dead but it could be the discarded exoskeleton.

The blood shrimp is a super addition to a reef aquarium adding variety, interest and colour.

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The Banded Coral Shrimp

There are a few shrimps that find favour with reef aquarists. Two favourites are the cleaner shrimps Lysmata amboinensis and Lysmata grabhami. Another is the banded coral shrimp, often called the banded boxing shrimp, properly called Stenopus hispidus.

Have a look:

http://commons.wikimedia.org/wiki/Image:Stenopus_hispidus_1.jpg

Where the common name comes from is partly obvious as the bands on the shrimp are quite clear. The ‘boxing’ bit comers from the way the pincers are held.

This shrimp gives the reef aquarist the opportunity to keep something ‘different’ and interesting. Of course, there must not be any livestock resident that could pose a threat to the shrimp. The shrimp is reef safe. It is very common in retail outlets.

The shrimp requires security and will often take up residence in a small cave, which is why the reef aquarium is a good habitat. It is used to fairly dim light but usually adapts quite quickly to the normal brightness of the captive reef.

Feeding is straightforward as the shrimp will take pieces of small de-frozen lance fish, mussel and the like directly offered to it. Once acclimatized the shrimp will normally rise to take the food from the aquarist’s fingers, though usually they are not quite as confident as cleaner shrimps which often walk on the aquarist’s submerged hand.

When the shrimp arrives at its new home it must be acclimatized properly. This is not because the shrimp is particularly delicate as it isn’t being fairly hardy in a good environment. Shrimps are sensitive to sudden changes in seawater quality so it is best to adjust to the home aquarium seawater slowly, and one good method is to use an air line and air line clamp. Empty half the seawater from the travel container and allow the aquarium seawater to drip in, the drip speed being short of a slow continuous trickle. Allow the seawater in the container to reach the previous level. Some aquarists carry out this procedure twice. When transferring the shrimp to the aquarium do not allow it to be exposed to air.

Unlike cleaner shrimps, boxing shrimps should be kept singly. If they are not, it is likely that the aquarist will end up with only one anyway. This is because males will fight. If it is definitely known that a couple are a pair then fine, but this would be unusual. Additionally, it is reported that if the boxing shrimp is kept with other shrimp types it is possible they will be aggressive and kill them. I don’t dispute this but did in one earlier aquarium keep two cleaner shrimps and one boxing shrimp in a 4 ft aquarium and never had a problem. Perhaps I was fortunate. The cleaner shrimps were noted to always give way and get out of the way of the boxing shrimp.

Another danger to the boxing shrimp is anemones. It would seem that the shrimp could be kept successfully in small aquariums and so they can. However, if an anemone is present the shrimp will sooner or later be caught as they have long antennae and need to maneuver.

As with other shrimps they need to molt. This is because there is a requirement to grow and the hard exoskeleton will not permit this. Therefore the shrimp discards the old exoskeleton and creates a new one. It is at this time that shrimps are most vulnerable as it takes a little time for the new exoskeleton to harden. It is likely the shrimp will go into hiding for this period. When the old exoskeleton has been successfully removed there remains a perfect replica of the shrimp. It is quite easy to jump to the conclusion that the shrimp has died.

If regard is given to the few restrictions mentioned the boxing shrimp will provide interest and entertainment for a long period.

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First Introduction – Fish Or Invertebrate

The majority of aquarists decide that the first introduction to their aquariums should be a fish yet does it need to be this way.

I fully understand why this happens and perhaps this is due to historic reasons where aquarists used hardy fish to assist in the cycling of their aquariums. Something which I am glad to say is not done anymore. Perhaps it is the movement and colour of the fish which draws the eye. There are many reasons as to why people choose a fish as the first inhabitant of their aquarium. It uis of course not up to me to sway their decision in any way but perhaps people believe that a fish has to be the first introduction.

On another note if the aquarium is a fish only aquarium then the aquarists will of course be introducing a fish first!

For the aquarist with a reef aquarium however there is another choice especially when live rock is used as the filtration but it does not matter what filtration is employed. Live rock even when matured correctly is not very sterile and therefore may carry opportunistic parasites. When a fish is caught in the dealers it is put under immense stress due to the catching, the bagging, the transport etc. When the fish is introduced to the aquarium its immune system may be lower than normal and in a reef tank filtered via live rock it may become prey to opportunistic parasites.

I appreciate that the above can happen at any time in the aquariums life however at the very start the aquarist is learning and if a fish is lost at the very start then this is sad for obvious reasons however the aquarist’s confidence in the aquarium and his/her own abilities and may give up the hobby.
There are certain fish which are more resilient than others however a lot of these fish – damselfish for example can become problematic later due to the aggressive nature and it is very hard to remove a fish from an aquarium with live rock in it!

Another method at the very start instead of fish is introducing hardy invertebrates.

By introducing hardy invertebrates first the aquarist will gain experience in acclimatisation techniques as well as stocking techniques. At the very start when the aquarist’s knowledge is low for want of a better word it is probably fair to say that a fair amount of tinkering will be employed. What I mean by this is that the aquarists hands will be in the aquarium a lot moving various corals around as well as the relevant water movement devices until they are satisfied that the conditions provided in the aquarium are suitable for the aquarium inhabitants.

If the decision is made to introduce invertebrates prior to fish then the aquarium, as with fish must be ready for the introduction of them. By this I mean that the nitrogen cycle has completed, there are no large algae outbreaks evident or they are under control and the water conditions are maintained in accordance with the recommended levels. For examples nitrates should be low as should phosphate levels. More than that the water conditions should not just be maintained they should be stable.

With the aquarist deciding to introduce invertebrates in the first instance the equipment purchased and installed should be capable of support the life in the aquarium. For example the lighting needs to be correct. This may sound basic but I hear of a lot of people trying to keep corals under lighting which to be honest is just not suitable for them.

At this point – actually a lot earlier the aquarist should know what corals, fish etc that they want to keep and should have based their purchases around this decision. At this point in the aquariums life you would not be looking at introducing an SPS coral like acropora etc as the aquarium is simply not ready for it.

At this point the corals you will be interested in purchasing are the ones which are not too expensive and do not have the colour of the majority of SPS corals. This is not to say that these corals are dull and colourless as they are far from it but when you compare prices you will see what I mean!

Speaking of purchase again I recommend that you build a relationship with a local dealer, another hobbyist or an online area (like Aquarists Online hint hint…) where you can go and ask advice as to what is suitable etc. Building a relationship with others is important as you can use their experience, their knowledge to your advantage o=plus you can learn a lot about the hobby and will hopefully not make expensive mistakes.

When selecting corals you are looking for corals which are suitable for the beginner. When looking you will probably see some exceptionally colourful species. I would probably stay away from these as there are some species which do not contain zooanthellae and require feeding for them to thrive. A good example of this is the sun coral. There are also other colourful ones which are probably for more advanced aquarists or aquarists who have had stable aquariums for a long period of time.

You have to remember that the aquarium is new and the water, rockwork, sand, glass, equipment etc all needs to age. You can always come back to these more colourful corals when your confidence has grown by maintaining a reef aquarium for a number of years.

In my opinion the list below details what I believe to be good ‘starter corals’ and are suitable for first introduction.

• Button Polyps
• Xenia
• Mushrooms
• Leather Corals
• Star Polyps

This does not mean that you should not introduce fish. I personally think that an aquarium with just corals in and no fish lacks movement however I think that perhaps more aquarists should introduce invertebrates prior to introducing fish to gain both confidence in themselves as well as giving the aquarium time to settle.

This of course also does not mean that you will not get problems when introducing fish at a later stage. You might but just remember to acclimatise them properly and use a quarantine tank.

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The Bubble Tip Anemone

There are a few anemones that find favour with aquarists and this is one of them. As well as the name in the title they are also commonly known as the four coloured anemone, the bulb tentacle anemone, and the bulb anemone. The proper name is Entacmaea quadricolor.

The anemone is one which requires good lighting as it contains symbiotic algae, and it is this algae that gives the anemone its colour. Good lighting is defined in the same way that lighting for corals is, and that is it must be sufficiently intense and of the correct spectrum. If the anemone is to be located quite low down in a deep aquarium then metal halides will be required.

Again in the same way as corals, good seawater movement is needed. This does not need to be particularly strong, just strong, moving the tentacles and swaying the body. Current from a power head should not hit the anemone directly.

The final requirement needed to settle the anemone happily in its home is to provide it with the correct position from a security point of view. When placing the anemone on the reef ensure that the anemone when fully open will not interfere with neighboring corals, but the most important point is to ensure that the foot of the anemone is located in a fairly deep crevice or hole, not a tight squeeze but a good generous loose fit. The anemone should anchor itself within the hole or crevice, which will also give it protection should it require it. It is unlikely that this will be needed in a home aquarium but the anemone doesn’t know this!

Failure to provide the named requirements, some of them, or one of them will either result in the demise of the anemone, or it will be very tiresome and start wandering around the aquarium looking for what is missing. I located an anemone in an earlier aquarium, meeting all the above needs, and it stayed put from the word go. Finally the anemone had to be removed as it just became too big.

Talking of size, the aquarist should be aware that this anemone could achieve a diameter of around 18″ (circa 45.75cm). Therefore it is not suitable for small aquariums; a length of say 48″ (circa 122cm) should be suitable.

It is my opinion that new aquarists without experience should not purchase this anemone (or any other) until such time as they have some experience. If the aquarist has kept an aquarium for a year successfully, that is, has maintained high seawater quality and the fish and corals have done and are doing well, then that is a reasonable time to consider an anemone.

Once in the aquarium a little time is needed for the anemone to indicate that it is settled. The indication is that it stays in one place, expands fully and is in good colour (meaning the algae are functioning therefore the lighting is acceptable).

Feeding is simplicity itself. First of all the anemone obtains nutrients from the symbiotic algae and feeding should not be overdone. When required, the anemone will accept a small piece of fish or mussel. This can be placed towards the mouth within the tentacles, when the anemone should respond and move the food to the mouth. Feed once or twice a week to start and build on experience.

This anemone in common with others contains nematocysts in the tentacles, which are like small harpoons that are activated on contact with a fish or shrimp. They penetrate the body of the victim and inject a toxin enabling the anemone to overpower and devour. There isn’t usually a distinction made for the aquarist’s prize livestock! Having said that, most fish seem to have an inbuilt instinct to keep away from the danger. I clearly recall becoming tense on more than one occasion when a lovely fish, intent on its search for food, seemed to be so, so close to the anemone ” but I didn’t lose any.

Many aquarists are keen to associate an anemone with a clownfish. Well, Entacmaea quadricolor is one of the anemones that act as hosts for clownfish. It is important not to overload an anemone with clownfish, usually one or maybe two is quite sufficient in an aquarium. No attempt should be made to host a clownfish until the anemone is known to be settled. The clownfish that are known to inhabit this anemone are Amphiprion clarki, Amphiprion ephippium, Amphiprion frenatus and Amphiprion melanopus.

It has been known, more than once, that a suitable clownfish has been placed in an aquarium containing a host anemone, only for the clownfish to totally ignore the anemone. Why this is I cannot say – is it because the fish was aquarium bred? If so, perhaps the fish doesn’t know it is supposed to live in an anemone! As said, I don’t really know. Fortunately, I have managed to obtain clownfish in the past that have been cooperative.

So if the aquarist has the experience and can provide the conditions, an anemone is worthwhile. If the anemone settles well and a clownfish (of the correct type) is introduced, then the aquarist will have the pleasure of seeing one of Nature’s strange and amazing combinations.

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Brine Shrimp – Should You Use Them In A Salt Water Aquarium

Feeding the livestock in a marine system is of very great importance. All living things need food to obtain energy and remain healthy. Without an adequate food supply – adequate in both quantity and quality – livestock will soon start to have problems.

Brine shrimp have been in use for many years. They can be obtained frozen and live and, though I haven’t seen any for a while, they are also available dry.

One of the tricks that can be employed when a new fish is reluctant to eat is to use brine shrimp. When they go into the aquarium the other resident fish chase them with gusto and often the new fish will become involved in this and take a few. If the new fish is on its own a brine shrimp or two dancing in the current is hard to ignore.

I would guess that the majority of aquarists use the frozen type. These come in a flat pack which is divided into segments, each segment is broken free as required. The segments can be cut down into smaller amounts according to need. Before the food is introduced it needs to be defrosted and this process should be done in seawater or a little reverse osmosis water. The food should be allowed to defrost on its own without the assistance of a microwave or similar. Some aquarists rinse the defrosted food before use.

The best frozen shrimps to use are those that are ‘enriched’. Brine shrimp is not particularly rich though it probably provides good roughage. Some aquarists insist on a product that has been irradiated, which means that there will not be any disease causing dangers present.

Live brine shrimp are usually purchased from a local store by the bag. The shrimp are definitely fresh and the storekeeper should be able to state their origin and if they have been enriched. Some aquarists are concerned about the possibility of disease. I used live shrimp for two years or so from a local store and never had a problem. I ceased using them as the supply to the storekeeper dried up. At that point I switched to frozen.

Brine shrimp are available dried. I did try them once and found them not to be particularly worthwhile for the simple reason that they had to be pre-soaked for quite a time or they would float around on the surface – once soaked they did sink but the fish were not overly enthusiastic. As said I haven’t seen the dried variety available for a good while. I also wondered about the nutritional value. Without any evidence I always had the feeling that this was poor.

Producing live brine shrimp at home is easy. All it needs is a suitable container with vigorous water movement, a convenient location and a supply of eggs. The eggs have become much more expensive (or they have in my area) and it may be found that the frozen variety is more economical. There are brine shrimp hatching kits available commercially, and these come with full instructions which are straight forward. Just don’t put too many eggs in like I once did: there’ll be so many brine shrimp they’ll need feeding themselves before they can be used. Using tiny newly hatched shrimp is good for corals and fish.

Brine shrimp are not a complete food in themselves, more of a supplement. There isn’t a reason why an aquarist couldn’t use them every day, but it would be better to use them along with other ‘supplements’, a good example is mysis shrimp. A fully nutritional food such as marine flake and the like should be the base diet. In addition attention must be given to the dietary requirements of livestock. Surgeon fish for example will usually eat brine shrimp without problem, but they need more nutrition as mentioned plus a good supply of suitable algae.

Brine shrimp is an excellent part of the marine aquarist’s food store. Stored and used properly it will add dietary variety and the fish seem to enjoy chasing it down.

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