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>
