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FAQs on Freshwater Crab Identification

Related Articles: Fresh to Brackish Crabs, Freshwater Crustaceans, Invertebrates for Freshwater Aquariums by Neale Monks, Forget Crawfish Pie, Let's Make a Crawfish Tank! By Gage Harford

Related FAQs: Freshwater Crabs 1, Freshwater Crabs 2, & FAQs on: FW Crab Behavior, FW Crab Compatibility, FW Crab Selection, FW Crab Systems, FW Crab Feeding, FW Crab Disease, FW Crab Reproduction, & Fresh to Brackish Water Crabs, FW Crustaceans 1, FW Crustaceans 2, Terrestrial Hermit Crabs, & Marine: Hermit ID, Hermit Behavior, Hermit Compatibility, Hermit Selection, Hermit Systems, Hermit Feeding, Hermit Reproduction, Hermit Disease/Health, & Crayfish FAQs, Crayfish 2, Crayfish ID, Crayfish Behavior, Crayfish Compatibility, Crayfish Selection, Crayfish Systems, Crayfish Feeding, Crayfish Disease, Crayfish Reproduction,

Thai micro spider crabs, and Kuhlis    3/17/13
hi WetWeb,
<Hey Jon>
Not a question but I don't see much info on the Thai micro spider crabs on your site, so thought I'd send over a couple photos. They are cute little guys. You may use the photos as you see fit - I took them so hereby give you free reign.
<Thank you>
Okay, since I'm here I will ask a question after all :) How would you catch a Kuhli loach in a heavily-planted tank ?
<Two nets (one in either hand), and carefully... so not to squish in the corner... Likely have to remove all decor, plants even>
thanks again for the site, y'all are a very helpful bunch of people.
We appreciate it :)
cheers
Jon Banquer
<Thank you for sharing. Bob Fenner>

Juv.

Goa land crab ID 8/21/11
Sir, I have found a crab in my garden it was crawling on the wall and have problem finding its details on internet hope u will let me know what type of species of crab this is bright pink colour black eyes. is it a rare species or a common one. pls let me know. I am from Goa India just happened to visit your site online while looking for information.
regards. sample pics and clips attached
Elvis John D'souza
<I don't know this species. It's clearly a land crab of some sort, perhaps a Gecarcinus species. But it isn't a species I've seen in the aquarium trade so can't offer you any better help than that. The zoology or ecology department at your local or regional university should be able to help.
Alternatively, a local natural history museum or nature conservation office. Cheers, Neale.>
Re: Elvis Goa India 8/21/11
thanks a lot
Elvis John D'souza
<Most welcome. Do read here: http://www.wetwebmedia.com/fwsubwebindex/fwcrabfaqs.htm
While crabs can make fun pets, they're mostly amphibious and cannot be kept with fish or each other. Review Cardisoma armatum online for the basics.
Cheers, Neale.>

weird hitch hiker 4/25/11
Dear
Neale/Bob/Oluwaojo/Sabrina/Chuck/Pedro/Donald/Mark/Sara/James/Mike/Wang/whoever is going to answer,
I got an unusual hitchhiker on my plants today. It appears to be a small white crab. About an inch in carapace size. I put it in my shrimp tank which has bee shrimp and cherry shrimp. It's sitting above a rock and waving it's claws in the air. What is it? Will it harm my shrimp?
Thanks
Jay
<There is a Thai micro crab, Limnopilos naiyanetri; check that out. Cheers, Neale.>
Re: weird hitch hiker 4/26/11

Thanks Neale, you got it spot on.
<Woo-hoo!>
Upon research I found that they are fine alongside dwarf shrimp. Do they do well on standard crustacean food?
<Not really. They are very much feeders on tiny particles. They seem to do quite well pecking at particles from finely divided structures -- notably mature sponge filters and the roots of floating plants (Indian fern, Amazon Frogbit for example). Given such structures and a mature aquarium, they'll consume a mix of infusoria, algae, and finely powdered flake food. But without such things to trap this food, they easily starve to death.
Definitely less easy to keep than, say, Cherry Shrimps.>
I saw a lot of unusual feeding suggestions involving squirting pipettes of infusoria in front of the crab.
<Yes, that's the sort of thing.>
Some sites claim they are filter feeders while a lot of others imply they are scavengers.
<Hmm, like Fan Shrimps, a bit of both.>
Can you shed any light on this or have you not kept this species?
<Do see above.>
Thanks, Jay
<Cheers, Neale.>
Re: weird hitch hiker 4/26/11
Thank you again. The tank is very heavily planted and it does have Indian fern but not Frogbit. There's literally hundreds of cherry shrimp and bee shrimp in my tank, along with about 30 Amanos, green shrimp and mandarins shrimp. I also already happen to have a fan shrimp, a bamboo. Any chance of outcompetition for algae with this many shrimp around?
<Some, yes, certainly.>
Aquarium is mature, 3 1/2 yrs old. I'll try infusoria and powdered flake. If he cares, I'll keep on doing it. I don't think he's going to go for the Indian fern, it's in the middle of the undergrowth - several Vals, java
ferns, swords, etc between it. He doesn't move from the clearing.
<These crabs do seem to prefer *floating* plants, and that, weird as it seems, appears to be their ecological niche.>
I'll try replanting nearer. Going to look out for Amazon Frogbit when I can. Sorry about briefness I'm writing on my phone. Read the website note on mobile emails, but hopefully this is clear enough, if not then sorry.
Jay
<Cheers, Neale.>

Crab identification 11/17/10
Hello, I was wondering if you could help me identify a large crab that I recently bought from Petco. They had it labeled as a "Thai Red Devil Crab" but all my internet searching on this name has not found any results. He is about 4 1/2 to 5 inches across with a purplish red shell. His left claw is much bigger than his right, but not quite as much of a difference in claw size as Fiddler crabs. On a side note, I was wondering if crabs use their large claw for anything other than attracting the ladies. Anyways, I currently have him in a 10-gallon semi brackish tank (he will be upgraded to a 25 soon) with a cave to hid in and one of those small turtle docks to allow him to get out of the water. Is this setup ok or should I switch to a terrarium? I also included some pictures of him and one of my crayfish for your convenience. Any help would be appreciated.
Zach
<Hello Zach. You appear to have a male "Thai Devil Crab". They're periodically traded but I have no idea what their Latin name might be. In any case, they get quite large, and they are notoriously aggressive and
predatory. They do appear to be more or less aquatic in the same way as many other estuarine crab species -- i.e., by choice they stay underwater, but that can venture onto land for short periods. An arrangement of rocks above the waterline that allowed the crab to bask under the light should it choose to would be helpful, but otherwise don't worry about providing this beast with a land area. Thai Devil Crabs don't seem to be amphibious in the same way as Soapdish Crabs or Red-Claw Crabs. One clue is their rather flat body compared to the much more boxy, deeper body shape typical of amphibious and land crabs. They do require brackish conditions though, SG 1.005 is ideal, and I'd also recommend using marine aquarium Iodine supplement at about 50% the recommend dosage. Although crabs are carnivorous given the chance, their diet should be distinctly mixed with plenty of green foods alongside meaty treats such as tilapia fillet and unshelled prawns. As for differences in the size of the claws, so far as I know this species has claws of similar size, so your chap has probably lost a claw at some point, and it'll be a few moults until the new claw matches the other claw in size. Crabs do indeed use their claws for all sorts of things, from signaling to one another through to dismembering prey, snipping off vegetation, crushing snail shells, climbing up things, and of course for nipping at anything that attacks them. Crabs are fascinating animals, among the Nature's success stories, and quite a sophisticated and modern group of animals despite their sometimes archaic appearance. Cheers, Neale.>

Re: Crab identification, salt 11/17/10
Hello again and thank you for the quick reply. I don't think my crab lost his claw in a fight as all the other crabs in the tank also had one large and one small claw. He also uses his small claw to pick up food like
fiddler crabs. His large claw has roughly the same proportions to his body as a fiddler but his small claw is a little bigger proportionately. If both his claws were the same size as his left I don't think he could move them. I'm sorry if you didn't get the picture I will paste it to this message. As for the salinity, should I use marine salt or is their a salt specifically made for brackish water? Sorry if that sounds dumb I don't know much about saltwater tanks.
Thanks in advance
Zach
<Hi Zach. The claw could easily have been damaged prior to collection.
While it is not uncommon for crabs to have dissimilar sized claws through accidents and fights, Fiddler crabs are exceptional in having one claw massively overdeveloped as a signaling/fighting tool rather than one for feeding and climbing. So far as I know, crabs don't do the lobster thing of having one claw for crushing and one claw for snipping. Yes: marine salt mix is what you need, not "tonic" or "aquarium" salt used for treating freshwater fish. Around nine grammes per litre should be ample, with iodine added. Without the iodine, large crustaceans are extremely prone to moulting problems in captivity. Iodine-rich foods such as Sushi Nori make particularly good supplements to their diet for the same reason. Cheers,
Neale.>
Re: Crab identification, sys 11/17/10
Hi sorry for so many questions (this is the last one) but how long can these crabs live in freshwater? The salt in his tank is "aquarium" salt. I might not be able to get marine salt for a couple days will he be ok until then? I don't know how long Petco had them in freshwater but he's been in my tank 5 days. Thanks.
Zach
<Hello Zach. "Aquarium" salt will do for a few weeks, but in the longer term the lack of calcium salts as well as iodine could cause problems. If you can, add 1 teaspoon baking soda (sodium bicarbonate) and 1 tablespoon Epsom salt (magnesium sulfate) per 10 litres alongside the aquarium salt.
These will provide some of the minerals crustaceans need for their shells.
Also, add the iodine, either in the water, or through foods rich in iodine (there are some special crab pellets available from companies like JBL).
Cheers, Neale.>

crab compatibility 11/19/10
Hello, I would like to thank you again for all the info on my Thai Devil Crab. I am going to get him some marine salt this weekend. Anyway, my question is would a devil crab be compatible with a Halloween
crab(Gecarcinus sp.)? I know crabs are aggressive but I figured that since the devil crab is mainly aquatic and the Halloween crab is mainly terrestrial they would pretty much ignore each other. They would both be in a 55 gallon tank, (half water half land) about 4 ft long and 1ft wide.
thanks
Zach
<Easy one this. No. These large crabs are extremely intolerant of one another and in a small vivarium like yours cannot be reliably kept together. When one crab moults, there's a good chance the other one will
attack it. Cheers, Neale.>

unknown crab, terr. 4/19/09
Hello,
I hope you can shed some light on my current dilemma and give me a few pointers and how to take care of this beautiful crab I rescued today. I received a call from a friend that works at PetCo. He says "I have this awesome crab that someone just dropped off in a bucket and have no idea what to do with it. Do you want it?" Of course being the lover of all God's creatures that I am, I said "Yes". Keep in mind, I have zero idea what I have or how to care for it.
<Usually not difficult with crabs. They need something very similar to what you'd offer frogs or newts: shallow pool of water to bathe in; lots of damp moss and rock above the water; a source of warmth; and an enclosure with a tight lid so they can't escape. Virtually none of the species in the trade is aquatic, and all will spend most of the time on land.>
I have six fish tanks, all freshwater and no crab experience. I have searched the web to find not much info. It looks a lot like a soap dish crab, same basic shape, but this one I have is so awesome in color. Not
plain reddish/brown like the pics I have seen online. One call I made said possibly a Thai Devil crab. I am attaching a photo. It is female, I do know that much.
<Very likely a Cardisoma species of some sort, so basically similar to the Soap Dish Crab in terms of being terrestrial, largely herbivorous, and highly aggressive.>
She is currently in a 20g tall tank with a mix of gravel and crushed coral.
<It's a land crab. You can easily tell land crabs from underwater crabs.
Land crabs have tall, boxy bodies. They have that shape to make space for the structures that effectively function as their lungs. By contrast underwater crabs are usually more flattened so they are streamlined and not pushed over by water currents. Another good clue is the back pair of legs; on underwater crabs these are usually flattened into swimmerets, basically paddled; on land crabs they are pointed, just like the walking legs.>
I have a submersible filter running and I have some rocks she can climb out onto so that she isn't constantly submerged and have given a healthy dose of aquarium salt.
<Not a brackish water species, so far as I know. I'd certainly not keep her in an aquatic environment. Honestly, she's a land animal.>
I read in a several of the forums that I may need to get iodine supplements and some different salts. Does she need a heater?
<Yes.>
Anyway, so far she seems to prefer being under the surface for the most part. Every now and again she pops up out of the water just far enough to inhale through her "nose" and immediately exhales through her back side. I want to absolutely do right by her as she has obviously had a decent life so far. Can't imagine someone just bailing on her as they did today. She is fairly good sized with her body being about 2.5" across. Many thanks in advance for whatever info you can help me with.
Quick
<Read up on Cardisoma species, and keep in the same basic way. These animals like damp, but terrestrial, habitats and feed extensively on soft fruits, dead animals, etc. Couple of inches of filtered water ample. Iodine supplements are useful. Cheers, Neale.>

Re: unknown crab 4/19/09
Neale,
Thank you so much for the super fast reply.
<Happy to help.>
Beautiful isn't she?
<And how!>
We are just amazed at her colors. I am real concerned about taking care of this crab. Ok, just a couple more questions. Is the 20 tall big enough?
<Should be ample, especially if you use lots of bogwood or whatever to create places to climb.>
I have a 55g that has a crack in the bottom that is not being used. Or is that overkill?
<I'm sure the crab would love that tank, but why not keep things simple and inexpensive for now?>
Is the gravel and crushed coral ok or should I get a bunch of moss instead?
Or both?
<Either. These animals aren't at all fussy. Wild animals burrow into mud.
They burrow into the mud along river banks a lot, so if they can dig, that's great. Here are the things that matter: Firstly, that you can clean the tank out easily. Some folks find "disposable" media like coconut fibre
the ideal in this regard, simply cleaning it all out before it gets smelly.
Other folks prefer substrates they can clean every couple of weeks. Either is fine. What matters more are [a] a hiding place; and [b] humidity. Provided they have these things, they really aren't fussed. So a cave or hollow ornament or whatever where they can hunker down periodically is useful, and as for humidity, a plastic drip tray or even a regular hood should take care of that. Within these restrictions, be creative!>
I have made her a larger land area by making a plateau out of the gravel and siphoning out some of the water out. Seems to work ok with the filter still circulating all the water through the raised gravel area. She wants nothing to do with the "land" area and dives right back into the water.
<Really? That's odd. Well, since I don't recognise the crab to species level, let your observations be your guide. She certainly should have land, but if she's nervous or otherwise fussed about something, she will feel more secure under water. Start off with a 50/50 mix of land and water, and see how you go.>
Maybe that's just what she is used to. I hollowed out a spot in the gravel so there is just a shallow pool. She is staying there for the moment. As far as heat, get a heat rock?
<I'd recommend an undertank heating mat as being a lot easier to use in this context.>
Of course that would require a real land area wouldn't it.
<Indeed. You may find that if the water area is big enough, heating the water, and allowing the warmed air to circulate, will do the trick. Really depends on how cold the air is in your part of the world. If you're in
Southern California or somewhere with a subtropical climate, merely warming the water would be adequate. Elsewhere, you really want to heat up the whole enclosure.>
Again, I really appreciate your input.
Quick
<Cheers, Neale.>

Re: unknown crab 4/20/09
Neale,
You are awesome.
<Modesty forbids...>
We live in Texas, usually around 74, 75 in the house all year round. Should be warm enough I'd think. She ate a nice piece of cantaloupe while we were making breakfast. I feel much better now that she has eaten something.
Here's a link to a site I found helpful as well.
http://aqualandpetsplus.com/Bugs,%20Patriot%20Crab.htm
<Have to confess that this isn't one of my favourite sites; while it has a page on just about everything, it also contains myriad errors and the writers seem to have a slap-dash approach to healthcare and animal welfare.
They seem to offer feeder fish to just about everything, which to me is a massive alarm bell that rings "bad fishkeeping".>
We will stick to the 20t for now as I am going to "give" the crab to one of our 12 year old twins. You are of course correct concerning manageability compared to the 55g. The other twin is getting a hand tame pair of
Fischer's lovebirds to "take care of". We all know how that works don't we?
<Indeed... an issue I've commented on here before; by all means share animals with children, but if any parent believes their child will genuinely shoulder all the work (and expense) they're likely to be in for a
surprise.>
Should be fair, we hope...
Again, thank you. We will let ya know how we progress. Have a blessed day.
<I do hope so! And to you, too.>
Quick
<Cheers, Neale.>

Re: unknown crab 04/23/09
She did not make it Neale. We are very sad. Thank you for all your help, it does not go unappreciated...
<Sorry to hear that. Sometimes the best is all you can do, but that's not enough... Good luck next time, Neale.>

Freshwater Invertebrates, ID? Hey guys I am trying to ID a crab that is appearing more and more frequently in Australian stores. It has been incorrectly identified by several stores as Amarinus lacustris (Freshwater spider crab). I suspect the supplier is keeping this myth alive *lol Anyway, the crab in question is often referred to as a "brown backed crab". Orange/brown body with a chocolate brown H symbol on its shell. claws of equal size and quite heavy set, not long/slender. It seems to get to about 2" shell width. I would LOVE to know the scientific name for this little beauty, as although I am sure I could keep it happy using general crab knowledge, it would be nice to know its specifics. Sincerely, Abbey AKA Callatya <Hey there, sorry it took me forever! http://www.fishprofiles.net/files/~adam/tanks.htm Right down the bottom of that page is a front-on view of that crab. I asked a large pet store and they said they are buying them under the name Holthuisana agassizi. I cannot for the life of me find any reference to this species online, so I thought maybe, just maybe, you guys might have more references that I have access too. Thanks for your help! < I have seen this crab at wholesalers referred to as "red clawed crabs" from Asia. Try looking in the internet under that name to see if you can find more info. -Chuck>

Red Claw Crab <Hi Anthony, MacL here. The only red claw crab I know of is actually a brackish crab often sold for freshwater. Is this what you have?> I purchased a red claw crab from a local Fish store about 2 weeks ago. I believe the crab is a female due to the very small claws. Anyway, recently she has had her abdomen hanging open. <Maybe releasing eggs?> I figure she was getting ready to molt, but she hasn't done anything for 2 days now. She has already molted once since we have had her and it didn't take long. She has plenty of different kinds of food. Also these past 2 days she is flipping herself over on her back. <Not a really good sign.> Can you tell me what is wrong? <I'm just guessing here but I think you probably have her in fresh water and she needs some salt. I also think it might be a difference in PH as well.> I have searched through the internet, but cannot find any information on Red Claw Crabs. <I did a search on Google and came up with tons of thing on them. You might try www.google.com> Thank you for your time and patience. <Anthony you might do the research on them and decide if it needs to be in brackish water or not and make a decision from there.> Anthony <An excellent site re this species: http://wrongcrowd.com/aquaria/crab/ RMF>

FW Crabs Hello again. Thanks for taking a look at my letter. I have a few more questions for you. Using the German crab ID page I found on your site, I have determined that my soap dish crab is the third Thai fresh water crab they have listed, it looks just like my little Carl, right down to the dark zig-zags on his appendages. It says it is of the Demanietta species, but that seems to include a lot of different looking crabs. How can I narrow it down further? < Do a Google search on the web using the Demanietta species you have already found. That should get you closer to a correct ID.> Anyways, I've started adding iodine to all my crab tanks. How often should I add the drop? daily? < Add the drop of iodine every time you change water.> The water I use is well-water with a softener. If this is no good, what type of water should I use? Would adding some sea shells add calcium to the water? < All crabs like brackish water. I would use the softened well water but add some sea salt and micronutrients at about 1/3 to 1/2 the dosage recommended for salt water.> I know the fiddlers prefer brackish water, does Carl need some salinity also? < You bet.> Should I change the water to brackish? < The sooner the better.> Would his feeder minnows tolerate the salt? < They are pretty tolerant to salt and would probably do OK.> He has not molted since I have had him, but I just figured he was big enough that he only molted once a year. Am I incorrect with this assumption? < Sounds like a pretty safe assumption.> How big is this guy supposed to get, anyway? What is this creatures lifespan? well, thanks in advance, Scott < They usually get about 2 to three inches across the body and will probably live between 2 and 5 years depending on how old Carl was when he was caught.-Chuck>

Crabby Confusion - Playing With Common Names - 10/11/2004 I recently ran across a Red Thai Crab in my LFS. <Hui. With so little English information on crabs offered in the aquarium trade, I fear "Red Thai Crab" is just about as descriptive as "Small, colorful fish" to describe a neon tetra.... Not your fault at all, just the fact of the matter.> I have never seen one before. It was huge and in fresh water, and obviously red. <Well, red helps quite a bit. Getting' some ideas, at least.> I have no idea what the scientific name might be, <Sad. But not unexpected. I haven't seen a single crab available for sale with a Latin name for a label.> and my search on the internet has proven well, let's just say made me hungry, I can now prepare crab 100 different ways. <Great! You can come make dinner, then! ;) > Now the meat of the email. <The crabmeat, as it were.> I have a brackish water tank with a Snowflake eel, a dragon fish, and some Sailfin mollies. I would like to add one of these crabs to the tank but...... I have no idea if it is truly a freshwater crab and more importantly will it eat my eel and dragon fish. <Well, let's try to explore *what* this crab is. Also, a tank size would be of some assistance - also, I'd like to drop a bit of a hint that your eel may prefer saltwater as it matures.> Does it require a spot to get out of the water on occasion? The size of the crab was a good 4 inches, could be bigger it was busy moving a large rock in the tank. <Alrighty.... You say "obviously red", easily 4", and sounds like a bruiser to be redecorating his digs. My first, best guess is Gecarcinus ruricola (possibly the genus name is spelled 'Gercacinus'....) Please see here: http://www.wirbellose.de/arten.cgi?action=show&artNo=115 . I have seen this species offered for sale quite a few times, now. Some problems with this animal - and *especially* in keeping it in an aquarium - to my understanding, this crab, surprisingly, is not very aquatic. In the wild, it rarely enters the water, and instead gets its moisture mostly from humidity in the air. To keep it totally submerged is a short life sentence. It should be kept in a terrarium with enough water available to be fully submerged should it choose to do so (for instance, low humidity). The water available can be plain ol' freshwater, but I think it might be prudent to offer a separate container of brackish water, as well. If I recall correctly, this crab gets big - roughly an eight inch leg span - and though not horrifically aggressive, I'm sure it would willingly pick off small fishes or land animals. Feed with aquatic meats, also non-citrus fruits and veggies should be offered. There is an Aqualog book by Uwe Werner available that has a (small) section on this crab.> My eel is about 18-19 inches long (of pure hunger) and the dragon fish is about 13 inches (odd fish there), neat how that fish eats. <Neat indeed!> Also I just bought a 150 gallon tank for my brackish system (have not changed it over from the 55 yet) Just how big will that Snowflake eel get? <Big. Quite big. I urge you to see here: http://www.wetwebmedia.com/FWSubWebIndex/fwmorayeels.htm and make use of http://www.fishbase.org as well. As you will see, much is dependant upon specifically what fish you have. Whatever your eel is, a 150 should be adequate; it's mostly just a matter of determining what kind of water it will need as it grows.> It was only like 5 inches long when I bought it and it just grows and grows and grows, oh and it eats and eats and eats, I love it. <Glad to hear it. Amazing animals, aren't they?> Thanks you guys for any info you can give me. <Please do write back if you wish, especially if my guess on the crab in question was off - a very detailed description of color, placement and size of the eyes (widely spaced? long eyestalks?), whether one claw is significantly larger than the other, and any details you can muster will help. And, of course, a picture is worth a thousand words! Otherwise, you might be able to ID the feller here: http://www.wirbellose.de/arten.html#Krabben .> Craig in Peoria ILL <Wishing you and your fantastic fishes well, -Sabrina in Boulder Creek, CA>

A Sesarma By Any Other Name.... Would Be A Pseudosesarma 10/26/2004 Hi guys... <And gals. Sabrina-the-freshwater-invert-freak at your service.> We need your help. <Well, what d'y'know, that's what we're here for! Hope to help you out.> We have been getting conflicting information on our RCC. <For our readers, that's "Red Claw/ed Crab", or as you've mentioned in your subject line, Sesarma bidens.... Actually, this animal is now thought to be more accurately Pseudosesarma moeshi. Just a fun tidbit.> One thing that everyone seems to agree on, is that RCCs are brilliant escape artists. <True. Most (all?) crabs are.> However, when we have been trying to research as to whether they actually NEED to breathe air half of the answers are yes, the other half are no. <Mm, not so much that they need to "breathe" air (all land crabs use gills and require high humidity - even hermit crabs, which carry a bit of ocean in their shell!), but yes, they absolutely *require* a land mass to thrive. They will not last long, forced to be fully submerged.... Or worse, fully submerged in a freshwater aquarium, as they are unfortunately sold to be. In addition to their need to get out of the water, they also fare much better with some salt in the water. Doesn't need to be much, but they do much better with a bit of salinity.> Could you please set the record straight for us? <Land mass required, yes. Most definitely. It will live for a time fully submerged, but will not thrive, and will not live long.> We don't want the little guy to die, but we don't want him to escape either. <Any chance you could drop the water level a few to several inches and offer a good-sized land mass (even a very large piece of floating wood) with lots of nooks and crannies to hide? This would likely be sufficient. I suspect that the reason they are so renowned for escaping is simply that they are desperate to find a way out of the *water*, not the *aquarium*. All the same, a tight-fitting lid is definitely called for. Do please try to accommodate this animal rather than returning him; you will be greatly rewarded with a fascinating pet, with just a little work. Perhaps even a small, 10-gallon tank as a dedicated home for him and an opposite-gender pal?> Thanks so much, <You betcha. I really hope you choose to make this work out - these are fun critters.> - Ian Fenn <Wishing you and your crab well, -Sabrina>

A Sesarma By Any Other Name.... II - 10/30/2004 Hello again, Gurus of Aquaria! <Well hello!> Thanks so much for your Red Clawed crab-help Sabrina. We finally found someone/place that knows what they are talking about! <Heh, or at least we *hope* we do! So glad to have been of service.> We were wondering if we could please have some help with our cichlid tank now. <Whups, not me.... I am cichlid-ignorant, for the most part. Chuck, our mega-awesome cichlid master is in possession of a duplicate email; hopefully he'll give you the answers that you seek. I'll truncate this now, and give you a big hearty "Thanks!" for all the kind words. Wishing you well, -Sabrina>

Mystery Crab - 04/06/2004 Hey guys <Sabrina the freshwater crusty-freak here!> I am trying to ID a crab that is appearing more and more frequently in Australian stores. It has been incorrectly identified by several stores as Amarinus lacustris (Freshwater spider crab). I suspect the supplier is keeping this myth alive *lol <Yeah, frankly, I'm still confused on that subject. Here's the only photo/info I've been able to locate on the web about this poorly documented little beast: http://www.nzfreshwater.org/crustacea.html (scroll down) and http://www.dlwc.nsw.gov.au/care/wetlands/facts/paa/plants/emergent.html (scroll down to "Cotula coronopifolia - Waterbuttons").> Anyway, the crab in question is often referred to as a "brown backed crab". Orange/brown body with a chocolate brown H symbol on its shell. claws of equal size and quite heavy set, not long/slender. It seems to get to about 2" shell width. <Any chance you can snap a pic of this guy to aid in ID'ing him? The following two sources may help you: http://www.wirbellose.de/arten.html#Krabben and http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm > I would LOVE to know the scientific name for this little beauty, <Me, too! I've looked through everything that I have to look through, but without a picture to go off, it's pretty tough to try to find a good ID. I would very much like to see what your fellah looks like!> as although I am sure I could keep it happy using general crab knowledge, it would be nice to know its specifics. <Agreed. Always best to know what your animals need - and crabs are pretty diverse.> Sincerely, Abbey AKA Callatya <Hope to hear back. -Sabrina>
FW crab from down under info. Hi, This isn't a question - I just happened across your website and noticed a question someone asked about Amarinus lacustris - a genuinely freshwater crab found in S.E. Australia. Here is a photo if you are interested. Its about 6-7mm across the carapace. Although I am no expert, I'm happy to answer any queries anyone might have, although you were quite right in your reply - there is little info available. It would be illegal to attempt to export this animal. <Thank you for this input. Will post on WWM. Bob Fenner>

Answer to a mystery query (FW crab) 8/26/05 Bob: <Actually, Sabrina with you, today> In answer to Sabrina's question about the "red crab" on http://www.wetwebmedia.com/swcrabidfaq3.htm from 8/13/05, I believe I have the answer. <My question?? Oh - OH! I see. Yes, that was in reference to the surrounding entries ("Mystery Crab") that I was helping Charlotte with.> I too bought what the LFS was calling a "fire crab" (or so it sounded with his slightly different accent from mine) for my nano. I tried Googling this and found nothing. Mystified, I posted a pic of him on reefcentral.com <I would love to see this image, if you can grab me a link. If it IS an Uca/fiddler, I might be able to get it closer to a species, for yah. Not necessarily likely, but there are some great references on the web.> and still everyone was baffled. It was when I went to a different LFS that I realized what it is I and others are buying: A female fiddler crab (my LFS who I thought was saying "fire crab" was actually saying "fiddler crab" but pronouncing it "FIDE-ler" and I misunderstood him). Some LFS call them red crabs. Again: orange, 1", walks sideways, black eyestalks, burrows in the sand. <Does indeed sound like a fiddler/Uca sp., as far as burrowing goes.> Mine has proven to be totally reef safe, hiding about 99.9% of her life. I've seen her for maybe a total of 60 seconds in 3 months! The females do not have the typical fiddler chelipeded and so look like something else. <Correct/agreed.> The problem with this is that fiddlers are supposed to be given a land/water environment, as they live in muddy mangrove patches and near the shoreline. Unfortunately, a few seem to find their way into the reef trade, and unwitting people like me and Sabrina wind up with them. <Mm, again, 'twasn't me.... "I just work here" <grin>. Though I do have a couple fiddlers.... but mine are in a large sandy terrarium with a 2g saltwater swimmin' hole. They seem to be doing quite well.> I'm sure she'd be happier in a terrarium, but she does just fine it seems in my nano reef. <If possible, you might consider setting up a land crab system. You wouldn't believe how much fun they are.> Hope this helps! <Thank you very much for this! And again, I'd love to see an image of your crab, if possible.> Alex <Wishing you and your firely FIDEler well, -Sabrina>

Mystery Crab (Again) - 09/01/2005 Hi Sabrina! First off, sorry to you and Charlotte for confusing you! <Oh, no worries!> Here are two pics of my crab when he was in my 5g. Hope they help! <Mm, some, yes.... I still think this is an Uca (fiddler), and it *might* be Uca ecuadoriensis.... though I'm by no means certain. A very cool little invert; thank you very much for letting us see the images!> Alex <Wishing you well, -Sabrina><<Am moving this to the marine section, since fiddlers are marine....-SCF>>

Amarinus lacustris, ID, habitat of a FW Crab from down under 03/09/07 Can you tell me what "Myth" was being referred to here in the question in the following paragraphs? If I understand correctly the myth was concerning Amarinus lacustris. I have been trying to get a few specimens of Amarinus lacustris for a long time. I try to track down every lead but this one is too cryptic for me to figure out what was being referred to this time.. Michael Hissom Freshwater Invertebrates, ID? Hey guys I am trying to ID a crab that is appearing more and more frequently in Australian stores. It has been incorrectly identified by several stores as Amarinus lacustris (Freshwater spider crab). I suspect the supplier is keeping this myth alive *lol Anyway, the crab in question is often referred to as a "brown backed crab". Orange/brown body with a chocolate brown H symbol on its shell. claws of equal size and quite heavy set, not long/slender. It seems to get to about 2" shell width. I would LOVE to know the scientific name for this little beauty, as although I am sure I could keep it happy using general crab knowledge, it would be nice to know its specifics. Sincerely, Abbey AKA Callatya <Mmm... well... this could be Amarinus... Please read here: http://www.google.com/search?q=Amarinus+lacustris&rls=com.microsoft:en-us:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7PCTA ... and am going to send your query to our resident FW crustacean expert, SabrinaF for her input. Bob Fenner>

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