FAQs on Freshwater
Crab Selection
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 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 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,
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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
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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?
<Yes.>
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).
<Agreed.>
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:
http://homepage.mac.com/nmonks/Projects/FAQ/2d.html
>
If I use reef salt, would I still need iodine supplements?
<Yes.>
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?
<Ample.>
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:
http://wetwebmedia.com/FWSubWebIndex/fwcrabfaqs.htm
and the linked crab files above. Bob Fenner
FW Crabs, sel./stkg. 716/10
Hello,
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
getting!
<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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