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Caring for Crabs

By: Dr Gareth Evans - Updated: 25 May 2016 | comments*Discuss
Crabs Water Pets Tropical Exotic Hermit

Crabs have been gradually developing a strong fan-base amongst exotic pet-keepers over recent years and have gone from being occasionally seen oddities to accepted members of the mainstream in a very short time.

Fairly undemanding creatures on the whole, a number of tropical species of both hermit and land crabs can be maintained very successfully in captivity and make remarkably good pets. With proper care, crabs seldom seem to need a vet and can live to the age of five – and even longer.

Housing Your Crabs

Whatever kind of crabs you keep, a good tank will make an ideal home; how it is furnished and arranged largely depends on the species of crab being kept. Most kinds will thrive in temperatures around 24-29C (75-85F).

Some crabs offered for sale are wholly terrestrial. Tropical hermit crabs – species such as the frequently seen Coenobita clypeatus and C. rugosus, for instance – are a prime example of marine crustaceans that have abandoned their watery way of life, in favour of the land.

However, although they may have turned their backs on the sea, they haven’t entirely lost a certain dependence on water – needing a humid atmosphere in their tanks to be able to breathe. In the early days of crab keeping, the advice to keep these tropical creatures warm was simply to buy a desk lamp and let it heat up the air in the tank. Unfortunately, of course, this tended to dry the whole set up out very quickly and the unfortunate inhabitants typically met an early demise.

If you provide a suitable flooring material – such as sand or bark chips – which will help hold moisture, mist regularly, make use of heating pads and fit a suitable lid to your tank, these problems are easily overcome and your pets will breathe easily.

Other kinds of “land” crabs – such as the West African Rainbow Crab (Cardisoma armatum) and the Indonesian Land Crab (Gercarcinus ruricola) – demand more direct access to water. While they naturally spend most of their lives on dry land, often in burrows beside rivers and brackish sea inlets, they need the chance to submerge their bodies occasionally, so their tanks need both a generous layer of floor material and a sizeable area of water to allow them to feel at home.

On the other hand, the various tropical fiddler crabs, which are to be seen being offered for sale from time to time are much more aquatic – though they must also have the opportunity to climb out of the water. Sometimes erroneously sold as freshwater pets, they need slightly salty water, mimicking the estuarine mud flats of their natural homes. They fare badly as single specimens being happiest when kept in true pairs; sexing couldn’t be easier – only the males have the oversized claw that gives them their common name; in females, both claws are the same small size.

Sand is probably the best kind of flooring material for these crabs, arranged in a sloping “land” bank from about six or eight inches (15-20cm) down to an underwater inch or two (2.5-5cm) to allow them to scuttle in and out of the water and make burrows as they do in the wild.

Whichever kind of crab you choose to keep, your tank will need a good secure lid; despite appearances, crabs are remarkably adept climbers and the Cardisoma species in particular are surprisingly strong and well able to push their way out of insecure containers.

Feeding Crabs

Crabs are natural scavengers, consuming anything edible that they come across. Never-the-less, hermit crabs and land crabs have a reputation for boring easily if presented with the same diet for any length of time, so it’s as well to try to vary things as much as you can. Vegetables, fruits, meats, cereals and cat food all seem to meet with their approval, but be warned – they are terribly messy eaters, so be prepared to have to clean up after meal times.

Fiddler crabs are a bit of an exception to this rule. Smaller in size – few make much more than 2 inches (5cm) across – their natural diet consists of microscopic particles of organic matter found in the sand or mud. In captivity they can successfully be fed on commercial crab food, freeze-dried or frozen shrimps, daphnia, brine shrimps, diced seaweed – fresh, or dried – and sliced fresh fish.

Whichever species you decide to keep, if you provide your crabs with the right conditions and proper care, you can be assured of enjoying the company of some fascinating – and fairly long-lived – pets for some time to come.

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I am a bioscience student about to catch (eriocheir sinensis) Chinese mitten crabs for study in Kent. They are a growing problem! I am intending to keep them in tanks in the labs and was wondering if i assimilate a muddy river bank with low level water (no saline) and a sand/gravel floor will this keep them happy long enough for me to study them. will i need to change the water etc regularly?
Tracy - 25-May-16 @ 11:48 AM
Hello and thank you for the information you have shared. No matter how much I try to find out about Rainbow crabs its never enough, not much information about them. My question is how much should a Rainbow crab eat? I have read that you should not feed them a lot as they don need it but should I feed it daily and if so how much do I need to feed it as my crab seems to have a very good apatite and is always looing for food. Also id like to know if its a female or male mine has no bright colours so I'm guessing its a female right? I also read that you can tell them apart from the belly but I could not understand what I was looking for. I had my crab for almost 3 yrs now and it only shade once, is that normal ? Thank you so much for your time . Rainbow Crab owner from Malta.
eeyore - 20-May-15 @ 11:21 AM
Hi my kids have found a crab from the Lower Glenelg river and are needing to know what it will eat and how is best to keep it. I hope this is enough information.
Doug - 18-Jan-14 @ 3:13 AM
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