The Porcelain Crab

Crabs can be helpful or not in the aquarium. Some of the larger crabs are not required as they blunder about causing damage and disruption. Others¸ such as some of the hermit crabs, are colourful, interesting and at the same time perform a useful job scavenging which assists in keeping the system clean.

Another interesting crab is the porcelain. This term is often thought to refer to one crab but this is incorrect, they are multiple. Their size is not a problem as they achieve around ¾” to 1¼”. There’s another two good reasons besides their size which makes them particularly interesting to marine aquarists. First, they are very colourful. Second, they usually reside in the tentacles of an anemone, or more unlikely down underneath it. So they are similar in that respect to clownfish.

Porcelain crabs come under various common names depending on which one it is. To take one in particular the common name is ‘dotted anemone crab’, or sometimes the general ‘porcelain crab’. The proper name is a tongue twisting Neopetrolisthes ohshimai.

http://www.geodia.com/gallery2/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=crab&g2_itemId=132

They are best kept in a reef system, obviously with an anemone. Anemones such as those inhabited by clownfish are appropriate. Though one or two of this type of crab are able to defend their home against clownfish, this one is likely to lose out and it is best if the aquarist makes the choice – clownfish or crab. They are both suitable for inclusion with an anemone. It is best that one crab is kept as two of the same sex will fight.* If it is known that two are a pair then fine.

In a high quality habitat they are hardy, but it would be best for the aquarist to gain experience and feel confident about aquarium general maintenance including seawater quality before proceeding. This is not so much for the sake of the crab – experience is required for the sake of the anemone as, at least in my opinion, though I note quite a few others of experience agree, an anemone is not the ideal starter for a beginner. If an anemone and crab are to be kept, it should be remembered that the anemone requires the proper lighting, though this is likely to be present in a coral reef aquarium.

Feeding the crab is not difficult. The crab is a filter feeder and to facilitate this method the crab is able to spread hair-like fan structures into the seawater. So to feed them the aquarist could target liquidized filter type foods over them. This needn’t worry aquarists however, as the crabs will also take small pieces of de-frosted food such as lance fish, shrimp etc. The crab will not require much food though feeding should be fairly regular, and any extra food the crab ignores will probably be caught by the anemone, which in turn requires feeding with the same kind of food in larger pieces but less often.

When considering livestock for an anemone, clownfish of various types are probably the choice of most aquarists. If a crab such as that described is chosen then the interest is just as high and the sight of the two life forms co-existing just as fascinating.

(*Ref: Marine Atlas. Helmut Debelius & Hans A Baensch)

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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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Tube Anemones

Tube anemones (Cerianthus sp) are fairly commonly seen in local fish shops (LFS’s). They are different and very attractive. They remind me a little of ‘feather dusters’ in how they live, and also of some fireworks in appearance. The ‘pretty’ fireworks that is, where colourful flames and sparks exit the tube a little way before curving over downwards. There are around 50 tube anemone species in the world.

In the aquarium they should prove to be generally hardy – the usual demands for a quality environment are required. The area in which they are located should not have strong seawater movement because of the long tentacles – it is better if it is fairly weak. The lighting that falls on the anemone should not be strong, but moderate to weak. There is another essential requirement and that is sand for them to bury into. The sand depth should be in the region of 3½” to 4½” (circa 9cm to 11.5cm), though deeper sand does no harm. The sand should be coarse and from coral. Those who do not want a decorative sand bed (the depths given are deeper than the normal decorative 1″ to 2″) could consider using a marine safe plastic box full of sand. The edges of the box would need to spread 2″ to 3 beyond the anemone’s tube edge. This could solve the potential for a dirty sand bed. A deep sand bed (DSB) is constructed of very fine sand and is not really suitable.

The anemone has a long tube which is made up of secreted mucus and sand. It extends down into the sand and forms a home and anchor for the anemone. As the tube is quite slender and pointed, it would be possible for it to come out of the sand, so the anemone can create an expanded tube or bulb at the bottom, which prevents this.

It has been reported that if the aquarist does not want sand in the aquarium a plastic tube is sometimes successful. The plastic should be marine safe and a little wider than the anemone, ensuring that the length is more than adequate. The tube can be placed in the aquarium – between rocks for example – where it will not visually intrude and the anemone put into it. Any plastic showing should be covered in encrusting algae growth fairly quickly and the anemone should hopefully be secure and healthy.

The anemone will be on full display when waiting for food capture. If a threat is perceived the anemone will disappear into its tube at very high speed.

As with other anemones, the tube anemones have defensive/offensive weapons. These are the nematocysts, or stingers, that lie curled like spring loaded barbed harpoons until released. They carry venom and this could cause problems if the aquarist does not exercise sufficient care.

The anemones must be located away from all other corals, colonial anemones etc as the sting is strong and could cause severe damage, even killing neighbours. The tentacles are long and therefore have a long reach. The anemones live singly in the wild and should be kept away from each other. Similarly, the aquarist should not put slow moving and less agile small fish in the aquarium, because if they come into contact with the anemone they are likely to become lunch or be badly stung.

Feeding is straightforward as the anemones will take small pieces of defrosted mussel, shrimp or similar – ensure the food is cut very small. Brine or mysis shrimp could also be target fed. The food just needs to fall among the tentacles. Do not overfeed, two perhaps three times a week is enough.

As with other types of livestock, if the needs of the tube anemone are met then the aquarist will be rewarded with a lovely and ‘different’ display.

The following link has photographs of these lovely anemones.

http://www.poppe-images.com/images/search_results.php?=Anemones&species=Cerianthus%20species%204

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If You Have Any Hermit Crabs Remember To Put Some Shells In The Aquarium

Hermit crabs are an excellent addition to the aquarium clean up crew. There are many different types of hermit crabs available and each one assists in the cleaning of the aquarium in a different way.

There are small hermit crabs which are excellent at getting into all the nooks and crannies and giving them a good clean. At the other end of the scale are the large ones which due to their size are able to consume more waste.

There will always be an element of cleaning that the aquarist has to perform themselves, for example cleaning the skimmer. I have yet to find something that will help me empty the skimmer cup!

Natural cleaning as in natural filtration in my opinion is a great way to go.

Hermit crabs as well as all all other members of the clean up crew are live animals however and therefore have a requirement to be looked after and it is our responsibility that we meet their requirements.

If there is not enough waste in the aquarium then we should feed them, if they get stuck then we should give them a helping hand and we should help them grow.

Personally I find hermit crabs fascinating. They move around the aquarium in their own unique way, bumping over things and if you have a close look at them they are strange looking yet intersting little animals. I don’t know if you have seen a close up macro shot at all of a hermit crab but they look like they should come from another planet!.

Hermit crabs like any other animal are going to grow and when they do they are going to outgrow their home – their shell.

They will actively look for another shell and if they take a fancy to one which another animal lives in then they will attempt to take it. The other animal could be a snail, another hermit crab or some other type of animal.

They may do this even when they have not out grown their existing shell – they may just take a fancy to having a new home. Much like we do when we purchase a new house.

To counter losing your snails etc then simply add some empty shells of various sizes to the aquarium. It is much easier for the hermit crab to move into an empty shell than have to either fight anohter hermit crab or drag another inhabitant out of it’s home.

If you do add shells then remember to add shells of various sizes.

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