FAQs on Freshwater
Related Articles: Fresh to Brackish
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, & FAQs
on: FW Crab Identification, 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,
Panther Crab (Parathelphusa pantherina) color forms?
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
Thanks for answering my questions!
<Most welcome. Cheers, Neale.>
Re: Calcium Supplements for Panther Crabs?
I know you told me about the cooked unshelled shrimp commonly used for
human consumption, but wanted to know a couple things. I've heard you
can also feed egg shells and cuttlebones to crustaceans to help them get
the calcium they need. Is this true?
<Potentially, but it depends if your crab will eat them. By themselves
they don't sound very appetizing!>
Which type of cuttlebone should I use, if any? Also, how can I help ease
the moulting process to help ensure proper moulting and survival?
<Use marine aquarium iodine supplement, at 50% the dose stated on the
How long does this normally take (moulting and hardening of new shell)?
<Varies dramatically with age. Young crabs may moult once a month, while
older specimens may essentially stop moulting altogether, and their
shells often look very tatty and encrusted with algae.>
Thanks for everything!
<Real good, Neale.>
Re: Calcium Supplements for Panther Crabs?
Okay. One more question. After a crab moults, how long does it take for
their new shell to harden?
<Hours, couple days, depending on species, temperature, diet, calcium
Essentially, how long should I wait until I start worrying about if the
crab is alive or not?
<Anything more than a week would be worrying. But keep crabs singly,
give them iodine, let them eat calcium-rich foods, and moulting should
happen without problems. It's when people either ignore their mineral
nutrition and/or keep them in groups (or with fish) that moults fail.
Re: Calcium Supplements for Panther Crabs?
I'm getting a male and a female Panther Crab and am planning on housing
them together because I heard the male impregnates the females when she
moults. Is this true?
<Yes; or at least, is standard for crabs generally.>
Should I separate them when they moult just in case or when she isn't
I am going to put them in a 20 gallon long which I've heard is able to
house two female and one male Panther Crabs.
<Hmm… I wouldn't bank on this, but I don't know for sure it won't work.
It's a case of "suck it and see".>
Malawi Blue Crab (Potamonautes orbitospinus)
Hello. I found this interesting crab and want some info. How big do they
<Big; 15 cm/6 inches or wider across the shell.>
Do they go through a larval stage?
<For this species, unknown to me, but some other Potamonautes are known
to have a completely suppressed larval stage, i.e., the mother holds
onto the eggs until fully-formed "mini crabs" are released.>
How would I get these to breed?
<Probably impossible under home aquarium conditions; see below.>
How big of an aquarium would I need to house one male and one female?
<This species is reported to be extremely aggressive towards its own
kind, much like practically every other non-micro crab imported into the
hobby. So keeping more than one specimen is a risky venture.>
Are they fully aquatic?
<More or less, but they are notorious climbers and escape-artists. In
the wild they are somewhat amphibious, resting in burrows above the
waterline, but mostly feeding underwater.>
What water parameters should I keep them at? I heard any parameters
Malawi cichlids can be kept at, these can be kept at. Is this true?
Lastly, what type of setup would you recommend for these crabs?
<A very, VERY secure aquarium, perhaps with a rocky island or two for
them to come out of the water if they want to.>
I want to breed these to supplement my income and for the occasional
treat (I've never had crab but my family loves crab and I want to try
some). I think these would be good to sale because they are big enough
to be eaten and they are relatively rare in the US and Canadian aquarium
<I'm not sure this species makes much sense for this sort of venture.
There are lots of other fish and shrimp species that can be bred at home
and make a decent profit when sold to retailers -- ask your local
retailer what he or she could sell profitably, and take if from there!
Dwarf Gouramis for example are a good fish species to try because the
farmed ones are so healthy, while some of the most popular shrimp
varieties like Crystal Red Shrimps still make a good price. As for
eating quality, do review carefully the literature here: home aquaria
are Salmonella incubators!>
Thank you for taking the time to answer my questions!
Re: Malawi Blue Crab (Potamonautes orbitospinus)
Thanks for responding so quickly. I did not know that part about
Salmonella. Thank you for telling me.
<No problem! Cheers, Neale.>
Halloween Moon Crab - Gecarcinus quadratus
I have two g. quadratus crabs - purchased both 12/2010. Keep both
together in 20 gal. long with coco fiber substrate, hermit crab sand
pile, coco huts/logs to hid in and live plants. Keep moving water
fountain and use mister for humidity. Tank temp. ranges 68 - 85,
depending on local weather. Humidity at 75% and up. Food offerings are
fresh fruit, veggies, hermit crab "cookies", live crickets,
shrimp, cooked chicken. Water is declor treated. I have recently
noticed that one of the crabs has stopped eating and is sluggish. He
still moves around, however, he is not as active.
<Coming up to moulting perhaps?>
Also, he dropped one of his rear legs that seemed damaged at the mid
He is usually the more aggressive crab of the two. What are signs of
<Typically the moult comes off all at once, rather than a pair of
legs at a time. In any event, moulting crabs drink a lot, which puffs
up their new shell, and then go hide somewhere. Immediately before
moulting crabs can feel sloshy if shaken.>
Neither crab has molted in my care. I have also noticed that the crab
is taking on more water and that the whitish material under his shell
on his backside and alongside his legs is extremely engorged.
Are those his gills?
<Probably not. The gills are inside the body, underneath the
"apron" part of the shell.>
The other day I found him upside down in the fountain. Thought he has
died. When I picked him up, he pinched me and spit water at me (why do
they spit water?).
I could feel water moving inside his shell. I placed him back in tank
and now heat tank with 2 75W "moon" bulbs and covered his
side of tank with paper for privacy. Crabs are located in very open
area. Do I need to supplement with iodine?
<Well, tricky to do with terrestrial crabs. You can get
iodine-enriched tablet foods for crabs and these would be good.
Otherwise, marine algae is good, e.g., Sushi Nor.>
Should I be adding marine salt to water?
<Not with this species, no, it's a freshwater
one I believe. If you wanted to be super-safe, you'd offer
one pool of freshwater and one pool of brackish water, and let the
crabs choose what they want.>
Have I made this crab sick with improper care?
<Probably not, but do be aware the other crab will likely kill, eat
the moulting one.>
Re: Halloween Moon Crab - Gecarcinus quadratus 12/8/11
Thank you for such prompt response. I will make arrangements to
separate the crabs until this is figured out.
I will keep the tank dark and limit activities with the potentially
moulting crab to just water changes and food offerings. I would think
that this will reduce his stress so that he can accomplish a successful
I will still keep misting with warm water to keep up humidity.
I took the fountain out and just have a pool of water (so in case he
falls over into fountain, he can flip over again so he doesn't
drown). I also have noticed last week that instead of brown poop logs,
he was eliminating some sort of greenish-whitish watery goo out of the
little chute under his mouthparts.
Is there any other signs of moulting that I should be on the lookout
for versus having a sick crab..... I will be relieved when he is back
to his crabby self again.
<Honestly, there's little to no understanding of crab health, so
all you can really do is ensure the right environment, a good diet, and
hope for the best. If the crab does get sick, there's nothing at
all you can do. We simply don't know enough (anything!) about
crustacean healthcare. Moulting crabs tend to be shy and retiring, for
obvious reasons, and so we as pet owners see very little of what's
happening. But there are not usually odd secretions, so the green goo
sounds odd. On the other hand, he may simply have eaten something
<You're welcome. Good luck, Neale.>
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.
Panther Crabs! 6/29/11
Hey there folks! As always, I have a few questions if you don't
mind helping me out with! I've looked far and wide for a completely
fresh water dependant crab! Parathelphusa panthernia
appears to be just what I've been looking for but is it all of what
little I've read it to be?
so here we go!
#1 T or F - I've read it does not require a land portion for its
habitat and can purely stay in a fully filled aquarium.
<More or less. They will crawl out onto floating plants and
above-the-water wood or stones, but only for short periods. So provided
there's at least a bit of land, even if that's just the top of
an internal canister filter it can perch on, it'll be happy.
Conversely, yes, it can climb, and yes, it will escape from an aquarium
given the chance.>
#2 T or F - It IS completely Fresh water, NO BRACKISH or full marine
<Is indeed freshwater. Hard, alkaline freshwater.>
#3 T or F - They grow to a decent size, 3 inch on just the shell, but
with legs around 5 inch, and thus the minimum tank size is 5 gallons
per crab (2 for a 10 gallon)
<Two will kill each other. One in an 10 gallon tank would be fine.
If you get one male and two or more females, allowing 25-30 gallons for
the first trio, and another 5-10 gallons per extra female, you should
be okay. But two males will fight.>
#4 T or F - They will eat or uproot plants, even the toughest leaves
are not safe from their grasp!
<Yes, they are omnivores and view plants as food. But tough plants
like Java fern should be okay, and fast-growing plants like Hygrophila
and Indian fern should keep up with any damage. Just don't expect
to keep one in an Amano tank!>
#5 T or F - They WILL eat any sort of dwarf crayfish, shrimp or fish
that it can catch or get a hold of somehow.
<Yes, they are omnivores and view any fish, shrimp or crayfish as
Anyone with knowledge on these crabs PLEASE help with these T or F
questions! I have a 10 gallon all ready and waiting for either these
panther crabs (preferred), dwarf crays, or Aegla sp. argentina (if I
could even find any), my tank is a low light set up so it has crypts
Anubias and soon to be mosses, so hardy plants for that matter..
I thought you would enjoy a little T or F trivia to change the pace of
your email reading haha! -Shovelman (AKA-John)
<Certainly makes a change! Nice animals, by the way. Cheers,
Re: Panther Crabs! 6/29/11
Thanks Neale! You don't by chance happen to be on tropical fish
forums as well? I always see "Neale" replying to many
questions and concerns in the oddballs section most frequently?
<Yep, that would be me! Cheers, Neale.>
Panther Crab, care 1/17/11
I recently bought a Panther Crab for my aquarium and I can't find
any information what so ever on how to take care of them.
<I assume this is Parathelphusa pantherina.>
My aquarium is relatively small... and they act quite strangely. The
only things I could find about them is that they like scavenging at
night and are known for attacking slow and big fish, though I guess you
could say that of most crabs.
<Yes, though like all crabs their diet is really very varied, with
things like whole lancefish and unshelled shrimp being particularly
important as sources of calcium. Use marine aquarium salt as stated on
the package, but at a half dose. This will ensure safe moulting;
without extra iodine, many crustaceans have problems moulting. Also
offer algae wafers and soft greens such as cucumber slices.>
This is not anything really important as I assume you are getting many
other e-mails of much more importance. If you have the time though and
you know anything I should be doing in specific to help these guys
<Standard vivarium set up required, though Parathelphusa pantherina
spends less time on land that most, so a few bogwood branches above the
waterline would be acceptable if space was limited. Hard, basic water
is important -- 10+ degrees dH, pH 7.5-8.5. Water temperature middling,
25 C/77 F is fine.
As with other crabs they're territorial and need hiding places when
resting and moulting; hollow ornaments and PVC tubes are ideal.
Don't keep more than one male per vivarium, and even females are
likely to be molested by the male if the tank is too small. Best kept
singly, really. Your 12 gallon tank should be okay for a single
specimen, but that assumes you keep it clean and perform regular water
changes. Keep the tank securely covered --
all crabs are very good at escaping!>
Extra Information: I'm not a aquarium expert so feel free to
My aquarium is only about 12 gallons and doesn't have many hiding
places. I have about 6-7 Neon Tetras in my Aquarium and 5 of this other
species of fish.. can't remember their exact name but they are
slightly smaller then the Tetras. Are they in danger?
<Yes; they're crab food for one thing. Also, the crabs need
hard, basic water unlike the Neons that want soft, acidic water. So not
good companions. All crabs are best kept -- in fact must be kept -- on
their own. Cheers, Neale.>
Re: Panther Crab 1/18/11
Wow! Lots of helpful information, thanks for the quick respond too I
appreciate it a lot! One last question.. if you don't mind. I
recently noticed this small... algae looking thing growing on a small
log I put in my aquarium. It is very dark grey in color and doubled in
size this week (Though it is still very small) It kind of looks like a
sea anemone but dark grey. It seems as if I accidently dropped a fur
ball into the aquarium and it stuck to a log and decided to start
growing! I would type this on Google to figure out what it is but I
don't think "Grey growing sea anemone looking thing"
would come up with many results. If you heard of this kind of thing
before it would be nice to know what it is, thanks.
<Without a photo, hard to say. Likely algae, but possibly fungus,
the latter usually colourless to grey. Algae can be a variety of
colours. If you send photos, remember, keep them no larger than 500 KB,
and if necessary, use an application like iPhoto to reduce
Also one last "extra information" I forgot to add in my last
message.. : I also have about maybe 5 Cray fish in my aquarium. Very
small crayfish.. I guess they are possibly those unshelled ones you
were speaking of.
<Hmm'¦ not really. While a crab *might* eat crayfish,
you'll likely find standard unshelled shrimp or krill from the pet
store better value. Buy frozen and defrost as required. Use regularly
but not to excess because the vitamin content of shrimp isn't good.
Balance shrimp against white fish fillet (ideally, tilapia) and algae
It kind of seems like right now I have a huge feeding ground for my
crab, and its food is everything in my aquarium. Problem is that I love
my Panther Crab and that crabs are my favorite type of aquarium animal
I could hope for, but I don't want to just catch every single fish
in my aquarium and crayfish just so my crab can have some peace. What
is my best option?
<Crabs require their own tanks. Don't delude yourself into
thinking otherwise. Small fish/crayfish will be eaten by the crab,
while bigger fish and crayfish can, will damage the crab during its
moult. Fish, crayfish, and crabs all need their own tanks. There
isn't a magic solution to this one. Cheers, Neale.>
Re: Panther Crab, mortuus est 1/24/11
Well, I don't have the photo, but something more important than the
small little ball has arisen! My panther crab.. died. I read that they
can live up to five years somewhere,
<Not even sure they've been traded for 5 years. But yes,
amphibious and land crabs do indeed have this sort of lifespan under
good conditions. They rarely live this long though because they're
usually kept in the wrong conditions, e.g., in an aquarium.>
and at first I thought he was just sleeping. Because he couldn't of
died in a position as strange as this, he died on his side, half of his
legs are holding him in the air on one side while the other half of his
legs face towards the surface. I thought he was just messing around
until I noticed he's been like this for three days now and
won't respond to anything that moves near him. I don't know
what could've cut down his life so shortly especially since I
don't think a small Neon Tetra could've killed him!
<Indeed not, but an aquarium designed for Neons will be inhospitable
to Panther Crabs, which are amphibious.>
He had some kind of strange... white.. don't know what else to call
it but, strange white object growing out of the right side of his
<Fungus most probably. Post-mortem.>
I thought it might of been a parasite or he could've been sick.
Could this of been the cause of his death?
Or is he just molting.. in a strange position for a really long
<No; moulting doesn't make the crab inactive, just shy. It
withdraws to its burrow, and then moults quite quickly, within a couple
of hours usually. It re-emerges once the new skeleton has hardened off,
typically within 24 hours. Crabs in captivity need dosing with iodine
used in reef tanks, though only at 50% the quoted dose on the
Freshwater Crab... some reading now! 1/5/11
I have a freshwater male crab in a ten gallon tank.
<Almost certainly neither a freshwater crab nor an aquatic crab.
Is this Perisesarma bidens by any chance?>
Along with the crab I have a sucker fish,
<Needs 55 gallons, assuming this is Pterygoplichthys
<Gobioides spp.? This is a big, brackish water fish that will die if
you keep it in freshwater; read here:
and a black fin shark.
<Is this Sciades seemanni? A schooling brackish to marine catfish;
This evening I noticed that the large claw and one leg was missing,
they look like they were ripped out. I was wondering if the crab is
suppose to remove its limb when molting? Or is there anything else that
could have happened that I am unaware of. The fish have lived in the
tank for a while now and been very harmonious, or so I thought.
Thanks Melissa B
<Melissa, if these animals are what I think they are, you have a
crazy collection of livestock in a tank far too small for them and
filled with the wrong water for most of them. Sooner of later
they're all going to die.
Read about the animals you've bought -- seemingly at random! -- and
rehome them. That they've lived together for a short while
doesn't mean much of anything, so you need to get real about these
poor animals and provide them with the conditions they need.
They're all fun animals in the right tanks, and I'm happy to
provide further information should you need it. 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.
<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
<Hi Zach. The claw could easily have been damaged prior to
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,
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
<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
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).
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.
<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.>
Please Help 11/7/10
Hi, Thank you for making this link available so that all us people who
have question can have them answered.
I just recently got into raising vampire crabs. I have
two males in a 10 gallon half land half water tank with a couple
fiddlers (they get along well).
<Tenuously... the Crabs will eat the Fiddlers in time>
A few days ago I bought a female to join my two males but three days
later I found her dead. The two males seem fine but I noticed tiny
white worms in the water.
I'm wondering if they came from her and that's why she died and
if that's the case I need to know what kind of monsters I'm
dealing with and how to kill them before they get my others. I've
been searching for hours but haven't found any clear answers,
especially for the vampire crabs. I would greatly appreciate a good web
<For worm ID?>
so I can gain more knowledge on what kind of creatures can infest and
or kill my new little pets.
<Likely cumulative stress... there are plenty of sites, info. on the
Net re this Geodesarma...>
Patiently awaiting your response. Thanks a bunch.
<The fiddlers need to live elsewhere... Bob Fenner>
Red Claw Crab Missing Limbs 10/12/10
I purchased 2 Red Claw Crabs from PetSmart.
<Perisesarma bidens'¦ and interesting, if aggressive,
brackish water crab.>
I believe one was male and one was female, do to the markings on their
underbellies, plus one had slim claws, and the other had fat, wide
<Do bear in mind males and females view each other as food except
After about a month, one crab (female) molted. She was seemingly fine
after the molt, with all appendages in tact. Two days later, 2 legs and
both front claws were missing. I removed the other crab (male),
assuming he attacked her. Three days later, the attacked crab died.
<As often happens.>
Am I correct in assuming the other crab attacked her?
<Possibly. When crabs moult they would normally hide in places such
as caves or bury themselves in leaf litter. Either way they'd be
out of view. Crabs view one another as potential meals, and in their
"soft" state they're easy targets. A lot depends on their
environment, and in a spacious tank with plenty of hiding places crabs
can moult successfully. But if you crab two crabs in 5 or 10 gallon
tank, it's hard for them to avoid each other, and if there
aren't any good hiding places, and I mean REALLY good hiding
places, not some upturned flowerpot, then they can, will attack one
Did the molt have anything to do with what happened here?
<Can certainly be a factor. But bear in mind lack of iodine is a
very common reason for failed moulting. Use marine aquarium iodine
supplement at 50% the quoted dose per gallon of water. Also make sure
their diet is calcium-rich -- a mix of whole lancefish, unshelled
shrimp, and suitable soft fruits should do the trick, along with
regular offerings of crustaceans foods such as those from JBL, Sera,
Would the lost appendages result in her death?
<Not in themselves, no, but lack of iodine can cause various
problems, deformed appendages merely being the most obvious
Also, I've read on your site that RCC are land crabs, but mine
stayed in the water most of the time.
<Well, they are land animals. In the wild they live in estuaries,
dipping into brackish or salt water periodically but foraging on land.
On the other hand, for a variety of reasons they may prefer to stay
underwater in a given aquarium, perhaps because there's only enough
dry land for one dominant individual. Cold and dry air can also stress
My tank set-up: 10 gallon tank, part land, part water. Sea salt mixture
added to water,
<How much? You really need brackish water, not "teaspoon per
gallon" amounts of salt. Use marine aquarium salt at not less than
6 grammes per litre (~3.8 US gallons), and ideally 9 grammes/litre, for
a specific gravity of at least 1.003 and ideally 1.005 or more at 25
with calcium and other trace elements especially for invertebrates.
<Iodine is the key, and yes, you do need iodine supplement.>
Utilized a terrarium filter to clean the water. Fed spirulina flakes,
bloodworms, krill, and crab pellets. No heater was used in the
<Well, that's one problem. They are tropical animals. The air
needs to warm and moist. Essentially you're creating a habitat
similar to what you would for tree frogs, except the bathing pool
contains brackish rather than fresh water. Apart from that, the coconut
fibre substrate will be similar, and the bogwood and plastic climbing
branches will be similar.>
After this experience, I do not believe PetSmart should be selling
<Difficult to argue against. But they are bizarre animals, and some
dedicated individuals have even bred them! The larvae need to be moved
into seawater conditions and fed tiny live foods, but it is
They seem to be aggressive towards one another,
<As are virtually all crabs.>
and their requirements go way beyond what the pet store would have you
<Same with Goldfish, to be honest.>
I wouldn't recommend them as a pet for the average person.
<The huge problem is that the "average person" doesn't
usually keep pet animals terribly well. How many dogs do you know that
get short, infrequent walks? How many parrots do you know living in
small cages? How many Goldfish do you know get in bowls or small
aquaria? You and I are different in caring about how animals are
maintained in the home; the average person often doesn't care all
that much -- or perhaps more charitably, doesn't understand how
badly they're treating their pets.>
Thank you for any information you can give! Your website is
<Kind of you to say so.>
Info On Mini Crabs <Micro Crabs> 6/11/09
While I have learned much of what I know of the aquarium hobby from
your website, I am unable to find information on micro crabs (aka Thai
micro crabs, mini crabs, hairy mini crabs, scientific name possibly
Limnopilos naiyanetri but I'm not sure on that).
From the little info I have been able to find on other sites, I am led
to believe that they are freshwater, don't need land, hang out in
plants, act like cherry shrimp, and like tropical temperatures -
I've read anywhere
between 64 Fahrenheit and 86....that's a pretty big range....
If someone knows about these adorable little guys, I would be ever-so
grateful if s/he would share that knowledge, or even direct me to a
legitimate informational site or book. Of course I would love to add
to one or more of my setups, but would never do that without first
learning about their water preferences, temperament, compatibility (it
seems they are more likely to be eaten by larger creatures than to
themselves?), nutritional needs, etc.
<Limnopilos naiyanetri, has just been discovered by hobbyists in the
early 90's. About all I can tell you is that these crabs are found
in pure freshwater in the roots of floating vegetation, such as water
hyacinth and fine leaf plants along river banks. They have hairy bodies
and appendages which collect mud and dirt and may function to trap food
particles. They are not carnivorous, and behave like Caridina shrimps
in their scavenging behaviors, where care and feeding are probably the
Googling will likely lead you to more information on the micro crabs. I
know of no book written on the subject and Bob and/or another crew
member may input here with additional info on the micro crab.>
Thanks in advance!
<You're welcome. James (Salty Dog)>