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FAQs on Freshwater Crab Selection

Related Articles: Fresh to Brackish Crabs Freshwater CrustaceansInvertebrates 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 Identification, FW Crab Behavior, FW Crab Compatibility, FW Crab Systems, FW Crab Feeding, FW Crab Disease, FW Crab Reproduction, & Fresh to Brackish Water Crabs, FW Crustaceans 1FW 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,

Is the Crab really freshwater? None are totally underwater animals... Most are brackish water, aggressive, and ALL are amphibious. Need to be able to get completely out of the water. RMF

Panther Crab (Parathelphusa pantherina) color forms?     11/1/12
Hey again. I read something and saw a few pictures of these crabs claiming to be different color forms. They mentioned red, purple, brown, and white clawed color forms in addition to the most commonly seen leopard spot colour form. Is this true?
<No idea, to be honest!>
Can they be different color forms of the same species?
<Or a closely related set of species.>
Are these actually the same species or are they different species? If these are the same species just different color forms, I may try to locate all of them and breed them all.
<Nice that you have a goal! But to avoid disappointment, do consider trying out something simpler, like crayfish, so that you understand the basics.>
Thanks for answering my questions!
<Most welcome. Cheers, Neale.>

Which Crab? FW sel.     10/31/12
Hello. I am looking into another possibility for my 135 gallon tank. I was wondering if there was any "true" crabs that have direct breeding (no larval stage) because I want to breed crabs and I'm not experienced.
<There are some, including the Potamonautes species we discussed earlier.>
I found one under the name Java Crab (*Potamon fluviatile*) but don't know if these are available anymore.
<Ask your local Fish & Wildlife department. For the most part, freshwater crabs and crayfish that can live in your local area are very likely to be restricted or banned outright. Both crabs and crayfish are notorious for escaping and become established where conditions suit. Once there, they're virtually impossible to eradicate, and often bring in diseases with them as well as acting as competitors for local species. Here in the UK we've for Chinese Mitten Crabs and American Signal Crayfish essentially wiping out the native European Crayfish.>
I would like some fairly large crabs that I can only put seven to 12 of those crabs in my tank (this isn't a necessity).
<Almost without exception, crabs are "one to a tank". The small species like Red Claw Crabs may be kept in groups for a while, but cannibalism is common. Fiddlers (Uca spp.) are somewhat more tolerant, but of course need brackish/marine conditions, not freshwater. About the only sociable species is the Thai Micro Crab.>
I would keep crayfish but I'm in Arizona where crayfish are illegal. :( I also want some that are somewhat cheap because I've never kept crabs.
<Have a look at Land Hermit Crabs. They're not especially difficult to keep, there are lots of books about them, and they are reasonably sociable provided you have plenty of empty shells so they don't have to fight over them.>
Thanks for your time!
<Hope this helps, Neale.>
Re: Which Crab?    10/31/12

I found a 3 inch crab (5 inches with the legs) called the Panther Crab.
It's scientific name is Parathelphusa pantherina.
<Indeed. An occasional import to the UK, too.>
Would I be able to keep 2 males and 5 females in my 135? I heard males are extremely aggressive but I figure - correct me if I'm wrong - in my 135, measuring 72 x 18 x 24 inches high, that I could have enough hiding places for them.
<Certainly sounds good in theory. But these crabs do tend to pick on one another during the vulnerable moulting stage. Be very, very cautious about mixing specimens.>
What is the maximum number of these crabs I could keep in my 135? What sex ratio would you suggest?
<More females than males to be sure, but the females are just as cannibalistic, even if they aren't (so) territorial.>
I saw plenty of info already on your website but I do have a couple more questions not on there. Do they dig burrows?
<Given the chance, yes.>
and What temperature do I need to keep the water at?
<Tropical; around 25 C is fine.>
I read the water should be alkaline and hard, but how many dH?
<Doesn't matter greatly; anything above 12 degrees dH should be fine.
Carbonate hardness will be important too. Provide calcium-rich foods as well, such as unshelled shrimp.>
Also, I presume about 8.0 pH?
I like to be as thorough and exact as possible so as to not "murder" the soon-to-be inhabitants. How would you go about breeding these?
<No idea. Do you know the PetShrimp.com site? The site owner is pretty clued up on freshwater crustaceans, and he'd be a good person to ask, perhaps via their forums. Some of the German forums are even better, so if you speak German, you'd probably find these forums even more useful.>
I know they have direct development (95% sure; correct me if I'm wrong).
I also know they are relatively cheap. :D Thanks for taking the time to answer all my questions and for bearing with me!
<Welcome. Cheers, Neale.>

Salt, plants, and crabs -- 07/21/11
Dear plant and crab expert,
<Yikes! Quite a combo, there'¦>
I'm converting one of my 10 gallon tanks to a paludarium. Most of the tank will be water (approximately 4 gallons), with lots of shelves on the back (for plants), and a shelf on the left with a ramp for easy access in case a land animal falls in the water.
<I see.>
I'm planting it with hairgrass, several crypts, and any other plants I can think of, even though I want it to be an Asian biotope (Samolus sp, baby tears, etc). I'd like to host red claw crabs (Perisesarma bidens),
<These are best kept as brackish water animals
and don't do well in freshwater indefinitely.>
Hermit crabs (Uca sp.),
<These are 100% brackish/marine animals -- whatever the retailer says -- and will die unless kept in brackish to marine conditions.>
and some aquatic insects (springtails, water louse, water striders).
<May not/will not be compatible with brackish water livestock.>
I can't really find a solid answer about how much salt is needed'¦ I was hoping 1 tsp of reef salt per gallon would be enough.
<SG 1.003 would be the absolute minimum; that's about 6 grammes per litre of water. Teaspoon measurements are very, VERY inaccurate, but 6 grammes is about 1 level teaspoon. Check it yourself using kitchen scales and act accordingly. Above SG 1.003 you'll have problems with plants; below, the Uca and probably the Perisesarma will be less robust, dying.>
I also can't really find out whether that would kill the plants or not.
<May well do unless you choose plants carefully. As it happens, Samolus valerandi is extremely salt tolerant. On the other hand, Hemianthus callitrichoides is not. Eleocharis species sometimes tolerate slightly brackish water but it varies between species. Hardy Cryptocoryne species like C. wendtii tolerate slightly brackish water, and C. ciliata is a true brackish water specialist. So do your research here, for example:
If I use reef salt, would I still need iodine supplements?
I'll also likely add some glass shrimp to the tank- if they get eaten, that's okay.
<These tolerate slightly brackish water well.>
Because the land area is built of shelves, is it ok if the crabs don't have a dry area to tunnel in? The terrestrial and aquatic plants should provide hiding places to help them feel secure.
<The plants will also be food for the crabs, especially the Perisesarma.>
Can you recommend any other inverts that would do well in this setup?
<Crabs generally don't cohabit with anything, and you would be very unwise to mix Perisesarma and Uca; the Uca are essentially non-aggressive (if territorial) deposit feeders that sift mud and algae, while the Perisesarma are aggressive opportunists that will view the Uca as potential food.>
I was also considering Nerite snails'¦
<Can work extremely well with Uca and shrimps.>
Thanks, David
<Cheers, Neale.>
Re: Salt, plants, and crabs -- 07/21/11
What about moon/Halloween crabs?
<Gecarcinus quadratus.>
I was thinking maybe mixing a mostly terrestrial crab with a mostly aquatic crab so the smaller ones could escape'¦
<Not a chance of mixing Gecarcinus quadratus with Uca spp.; do understand that crab species DO NOT cohabit in the wild, and most view one another as either rivals for living space or potential meals. There is an ample literature on this based on crabs in reef tanks; do read.>
It's ironic to me that Uca might be less likely to eat plants, but prefer more salt'¦
<Hmm'¦ not really ironic, merely a reflection of the fact these crabs come from beaches and salt marshes where freshwater aquarium plant species are absent.>
I might have to decide whether to kill my plants with salt or serve the crabs a salad bar. It's a shame. I might end up having to scrap the crabs altogether,
<Do look at Thai Micro Crabs.>
and go with Cambarellus Patzcuarensis var. Orange, also known as the dwarf mexican crawfish.
<A fine beastie, though irregularly traded.>
At least it's plant-safe and peaceful according to everything I've read.
<Hmm'¦ the smaller crayfish are less aggressive and less destructive, but it would be unwise to assume non-aggressive and non-destructive. Potentially safe in mixed species tanks, but do bear in mind these have only been in the trade a year or two, so there's very little experience to draw on, and certainly not every combination of crayfish, fish, and plant hasn't been tried.>
Not sure if it would ever leave the water though..
<Fully aquatic.>
I don't want the land area to go to waste.
<Paludarium systems tend to work best with frogs, to be honest, rather than inverts. You might consider tree frogs alongside, say, similar sized aquatic frogs or newts. Mudskippers are of course another possibility, and can, if species are chosen carefully, cohabit with Uca spp. and certain brackish water livebearers, such as Mollies. Provided the plants above the waterline are insulated from the brackish water and watered with freshwater, there's little risk of salt poisoning them, and conversely, there are true brackish water plants that might be placed under the waterline to green things up there. Cheers, Neale.>
Re: Salt, plants, and crabs  7/23/11

Sorry, I've been doing a lot of research. I think instead of giving the fiddler crabs (Uca sp) the minimum amount of salt, I'll give them whatever is ideal. Do you think 1.008-1.010 would be about right?
After a lot of research, I've found a list of plants that should survive at those levels... I'll put it here so you can share it with others. I assume some of these plants won't make it, but most should, as long as they're
acclimatized slowly.
Variegated Acorus (Acorus gramineus var. 'variegatus') Terrestrial/Emersed
Cryptocoryne pontederiifolia Terrestrial/Emersed
Crinum Calamistratum Submerged
Lilaeopsis novae-zealandiae (Microsword) Terrestrial/Emersed
Glossostigma Terrestrial/Emersed
Java Moss Terrestrial/Emersed
Java Fern 'Windelov' Undecided
Anubias Nana Emersed
Azolla Floating
Various Crypt species (already had) Submerged, will allow to grow emersed
Hairgrass Submerged
<Would be very, VERY surprised if most/any of these would survive above SG 1.005 at 25 C/77 F. Would strongly recommend you run the tank at SG 1.003 at 25 C/77 F to start with, using those plants. That's just short of 20% seawater, and more than ample for most brackish water fishes and livestock.
It'd be acceptable for your Fiddler Crabs, and being relatively benign animals, you'd have lots of options for things like Endler Guppies, Black Mollies, or, if you can get them, oddball livebearers such as Micropoecilia parae melanzona, Micropoecilia picta, and Limia nigrofasciata.>
For livestock, I'm thinking (I know, I can't seem to make up my mind!) 3-5 Fiddlers, 5-10 opae'ula shrimp AKA Halocaridina rubra (I'll have hiding places to let them get away from the fiddlers in case they think they're food)
<Very likely. Do bear in mind Cherry Shrimps adapt well to slightly brackish water, and in fact virtually all shrimps are worth trying at low-end brackish water.>
In addition, Fiddlers are mostly Diurnal, while the Opae'ula shrimp are mostly nocturnal. To wrap it up, I think I'll throw in a couple horned/corona Nerites and a ghost shrimp.
<Clithon corona, Clithon sowerbyana and Neripteron auriculata would all thrive in brackish water.>
The tank is a 10 gallon. I know they like to dig, but I think they'll have to settle for man-made tunnels made out of 1/2" PVC pipe.
<Cheers, Neale.>

Hey, I have some questions on fiddler crabs and red claw crabs.    7/22/11
<... Okay... have you searched, read on WWM re already? Bob Fenner>
re: FW, BR crabs, rdg.    7/23/11
I have but I don't think my questions are on here. I'm wondering mostly how well red claw crabs and fiddler crabs do together
<Not at all... is this a brackish system?>
and how many I could have in a 20 gallon long? I'm also wondering if red claws are more shy than fiddlers bc I see my fiddler alot <No such word> more.
<Go back, read on WWM re these species:
and the linked crab files above. Bob Fenner

FW Crabs, sel./stkg.   716/10
I was wondering what are some species of freshwater crabs I can put in a half land and half water aquarium?
Thank you, Dante G.
<The short answer is no. The standard crab species of the trade are the Red-Claw Crab, the Fiddler Crab, and the Rainbow Crab. The Red-Claw and Fiddler Crabs are both brackish water species. Rainbow Crabs are much too
large for anything other than their own vivarium, as well as being very predatory and aggressive. The Thai Micro Crab, Limnopilos naiyanetri, is a truly aquatic freshwater species that can work well in aquaria. But it is very small and easily damaged by anything larger than Dwarf Rasboras, Boraras spp. Some retailers here in England stock larger aquatic crabs, typically Parathelphusa species like Parathelphusa pantherina, but these are quite big and quite predatory, and not really suitable for community tanks. Cheers, Neale.> 

Crab? Non-sel.    12/2/09
Hello Crew! <Hello.> I got a small aquarium crab... Well that's what the petstore said anyway. I Heard that they needed more land than water. <Yes, and could even need brackish water. But without knowing what type it is,
it's impossible to know.> I have mine in a 10 gallon aquarium with some fish. It is always hiding in a rock. Would it be better to put it in a 1.5 gallon fish bowl with a small cup of water or leave it where it is? <This wouldn't work either -- you'll be unable to heat, filter such a small amount of water, and we still don't know the actual needs of this animal without an ID.> I can't afford to buy it a big aquarium. <I'd take this guy back to your store.> If I would have known that it was not an aquarium crab I would not of got it. I wish the petstore would tell you what you are
<This is why you never walk in and buy anything without first researching it and its needs... sure, it would be nice if the store would provide correct information, but it still surprises me how many folks walk into a pet store and take on responsibility for a life without knowing anything about the animal they're buying. I'd take this crab back to the store. --Melinda>

Crustacean for a Community Tank - 05/21/2006 Hello folks, <Hello, Doug.> I've been reading your articles with interest but I still am unsure about what I should do with regard to finding a suitable crustacean for my community tank. <Someday we'll have a shrimp article up....  just (finally) wrote the thing.> This is a freshwater tank, 20 Gallons, 2+ years old, nice and stable. Right now I have 5 Rasbora tetras, 6 cardinal tetra's and one fairly large Chinese golden algae eater (5" long). We added the Cardinals a month or so back and they are doing fine. We wanted to get some kind of crustacean to complete our community but are not sure what would be best after reading about predation of tank mates. What do you think might work in this situation? <LOTS and LOTS of options....  Any shrimp from genera Atya, Atyopsis, Caridina, or Neocaridina....> I had thought of a Hammers cobalt blue lobster but after reading more about it realized that it would probably be the sole tank occupant in short order. <It would.  Stay away from any crayfish/"lobsters".  If you want something big and beefy, for a 20g tank, maybe look for Atyopsis moluccensis, the "bamboo" or "wood" shrimp.  A 20g tank is suitable for a male and a few females.  Or if you want something bright and tiny, look for "cherry" shrimp (Neocaridina denticulata sinensis v. red), "Rudolph"/"red-fronted" shrimp (Caridina gracilirostrus), or maybe "crystal red" shrimp, (Caridina sp.).  There are plenty of other small shrimp species that are less colorful, and most any would be of use here.  I do hope you are able to find a fun and pleasing pet to add!> Thanks for your advice.  -Doug <Glad to be of service!  Wishing you well,  -Sabrina> Online Freshwater Livestock Store? - 08/19/2005 What is a good web site to order freshwater fish/snails/crabs online? <As far as fish are concerned, you might try http://www.liveaquaria.com/ .  Crabs - please keep in mind that there are NO truely aquatic, freshwater crabs available in the hobby in the US, to my understanding....  ALL are brackish to marine animals, or absolutely require a land mass....  For some pretty neat fish and inverts, http://www.franksaquarium.com/ .  Some really awesome North American natives can be found at http://www.jonahsaquarium.com/ .  Hope you find what you're looking for!  Wishing you well,  -Sabrina> Just a quick question, missing livebearers post holiday  7/14/07 Hi, I currently own a ten gallon tank with a few platies and a guppy inside it, along with a few platies that are small. I went on vacation and notice that a few are missing. <Sorry to hear that. Be sure and figure out *why* before adding anything new. Check water chemistry and quality, for example, and double check you're using the right food, i.e., something vegetable/algae based rather than generic flake food.> I think they might be dead, and I just want to know your suggestions on what might have happened... <No idea without more details. Water chemistry, water quality, number of each species, how long you were gone, what foods used, etc....> ...and what kind of crabs and shrimps are compatible with them. <None. Crabs are [a] amphibious so need somewhere to walk on land and [b] predatory. Shrimps can work with small fish but they are generally delicate and if you can't keep guppies alive then you're probably not at the stage in your hobby where buying shrimps would be worthwhile. That is, unless you don't mind the shrimps being dead in 4 weeks. Seriously, they need excellent water quality, the correct diet, and safe places for moulting where they can't be molested.> I usually leave fry in the tank instead of separating them and I want a few to live, are these good to add to the tank? <Don't understand this. Do you mean the crabs and shrimps are good to add to the tank? If so, no.> Or are they bad like Albino Aquatic Frogs? (I had bad experiences with them) <Not "bad" but just wrong for you and your aquarium. Crabs need their own vivarium a bit like something used for newts or frogs, with some water for bathing but also some dry land for social behaviour and feeding. Shrimps are really something for the semi-advanced hobbyist. Most of the ones sold end up dying within a few weeks when thrown into generic community tanks. Cheers, Neale>

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