Tai Devil Crab: Need Help

[FishySarah]

Hi. I recently aquired a Tai Devil Crab, also known as a moon crab or soapdish crab. She is in an unfiltered 10 gallon with about two inches of water in the bottom, and I know that keeping up with water changes is a must.

First off- should I get a small submersible filter for her? or would the water currents agitate her?

Second- the lfs said she's a freshwter crab, but I read online that they need brackish water. Then I read on another site tha either is fine. Does anybody know? If brackish, how much salt should I put in?

Any info would be great.

 

[Kevin_D]

Are you able to get a picture? as It may help getting it identified.

Most Crabs sold as Thai Crabs are a brackish, semi-terrestrial species, Pseudosesarma moeshi (formally Sesarma bidens)

I have seen Heterothelphusa fatum sold as "soapdish crabs" though, and they are true freshwater. Rainbow Crabs (Cardisoma armatum) has also had the common name soapdish crab I think? they need more or less the same care as Gecarcinus sp. theres info on them on my site,

[URL="http/www.exoticpetsuk.com/cardisomaarmatum.htm"]http/www.exoticpetsuk.com/cardisomaarmatum.htm[/URL]

Moon Crabs are another name for Halloween Crabs, Gecarcinus sp. they are also semi-terrestrial and can be kept with fresh or brackish water.

A small filter would be useful, the water will also need to be heated to around 24c or so, though if its H. fatum they can be kept cooler apparantly.

 

[three-fingers]

Those are just another name for rainbow crabs?

If that's the case, a filter would be nice, it only has to be a tiny cheap internal - but there's bigger issues.

Cardisoma armatum is mainly a land crab that should have some water to soak itself in when it chooses - preferably brackish water. If you could set up the tank so that is mainly land (~75%) and just have a small area for brackish water with an tiny internal filter - that would be the best kind of set up.

The water area can just be a tub, as long as it's big enough for the crab to soak itself fully and the crab can access it. If the has no filter you will need to change the water every day.

The salt used has to be marine aquarium salt to provide the the right minerals, these guys live mainly in rivers near the coast or the coast itself. It doesn't have to be very brackish at all, since they can live in freshwater - it's just not really a good idea for people to try it in aquariums. 3 to 5 grams of salt per litre of water would be fine .

 

[Kevin_D]

Ive kept my Rainbow Crabs in purely freshwater (around 2/3 of the tank is land) for around 6 years now, one is huge, at least 20cm across. They were both very small when I got them, they moult every 6 months or so in the water, and have never had any problems (other than one losing one its claws a few years ago in a fight with the larger one, which grew back the next moult.)