I'm thrilled to find this thread. I obtained six of these charming little crabs just a short while back, and have already lost one, no idea why. No idea whether it was male or female either. I have seen one feeding in the roots of a water sprite, the others I have not seen at all. There's a large piece of driftwood in the tank, a 5 G, and they seem to hide under it. They are nearly the same colour as the wood. I've been using the tank as a brooder for Ghost shrimp and currently have a number of one/two week old shrimplets in there, plus one Blue Claw Whisker shrimp who is much to canny to catch.
Moon sand substrate, loads of large frogbits, giant duckweed and water sprite, so lots of hanging roots for them. Been feeding very sparingly, as there is little mechanical filtration. Filters are a sponge, inside corner and small Fluval power unit. Being concerned about shrimp larvae being sucked into filters, I covered the latter two filters with 100 micron filter felt and stitched it on, so it gathers only microscopic detritus on the outer cover for the most part. Thus most of the filtration is biological. I do the odd WC, usually with a air hose stuck in the sponge filter uplift, to avoid sucking up shrimplets. I recently learned there are amphipods in this tank too. Don't really mind, they are kind of cute, and do not seem to be able to catch shrimplets.
So far, I have not been able to observe the crabs enough to have a prayer of sexing them, but I am most anxious to attempt to raise any eggs that may hatch, assuming I have both sexes. I'm going to read the papers that are linked here soon as I finish this. I too was wondering about brackish water for the eggs. While my Ghost shrimp have done fine in FW, my Whiskers have not, and I was going to do a brackish tank for them, in hopes they are similar to amano shrimp. They and the ghost shrimp are certainly breeding well in my 30 G main tank. All my tanks are fairly heavily planted at this time, with either eco complete or moonsand substrates.
Local water is quite hard and tends to a high Ph, close to 8 as it leaves the tap. I use mainly conditioned tap water, and so far, everybody seems quite happy, but the crabs are in the small brood tank, which tends to become more acidic with time and because I do fewer WCs. I think likely the big piece of wood in a small volume of water is doing the acidifying.I top up with distilled water, but I do WC with tap. The shrimp so far seem not to care about some fluctuations in their conditions, but I worry about the crabs. I have another tank ready to go, also 5 G, no fish, but it also with a few amphipods.
I have been feeding an assortment of sinking crustacean pellets, algae tabs, liquid invert food, meant for corals, green water and finely powdered spirulina mixed in water, mainly to feed the free swimming larval stages for the Ghosts. I feed those last three to my clams as well. There are snails in all the tanks.. pond, mystery, horned and zebra nerites. I thought it might be fun to try hatching some nerites in a brackish tank too, though to date I have zero experience with salt water of any kind.
If anyone on here has any suggestions on what conditions I should aim for in my new crab tank, please let me know. However, since it is difficult to fight the way the local water likes to be, and I am not in a position to afford RO water, I am hoping they are able to adapt to what I've got. I have a small distiller, gives me a gallon a day when I run it, but it's not enough to keep a tank going non stop without any tap water being used. Could maybe do half and half if need be. I do use it for top ups to avoid making the water any harder than it already is.
Any and all suggestions most welcome. I would be beyond ecstatic to succeed in breeding crabs. Just having the Ghost shrimp morph and survive was a huge thrill as I am quite new to shrimp keeping too. I later found better than half a dozen Ghost shrimp survived in my 30 G tank as well, despite the hazards of the filter, the pump, the danios, kuhlie loaches and three dozen odd shrimp that are also in there. Filtration may not be as big a hazard as I feared it might be, but I'd still make every effort to prevent any eggs or larvae from accidentally being sucked in. There is even 55 micron felt available to make filter covers with. In my main tank, all I did was make sure to stuff some intake grates with coarse sponge cut to fit, to prevent baby shrimp from getting sucked in, but I didn't cover the slots on the lid, only the ones at the front and lower edge. I must confess that the half dozen survivor Ghosts are likely all that's left out of, probably close to one hundred eggs that were let go in there, so it's not a great rate, but I was amazed that any managed to live.
Also, any suggestions on how to actually see my crabs without stressing them too much. They've been in their tank only for a week, so I hate to bother them just yet, but I want to see if I can discern the sexes and also whether they're eating. Would simply raising the piece of wood onto a couple of small rocks be likely to help me see them without taking away their hiding places ? There are no rocks to speak of in this tank, just the sponge filters and the big driftwood piece that goes from the front to rear corner on the diagnonal. Has a lot of ferns tied to it and some mosses, but not much has had a chance to become solidly attached.