Crabs!

[knxtninverts]

I am getting more and more into invertebrates. First shrimp, now crayfish and crabs.

I started with 2 female red claw crabs I found at a fish store, a trusted local store. They were in an aquarium with fish. After confirming they would be ok with my fish I bought them and put them in an aquarium with fish. They spent their time hanging out on top of the heater or behind the power filter, with just their little legs in the water. They came down at night to search for food. One dissappeared a few days ago, some smallish pieces of possible crab or crab molt but no sign of the crab. I'm thinking the fish ate her. Since I've gotten them, I found out they do best with a brackish setup with access to land/air.

The remaining female was moved on Thursday to a 10-gallon aquarium with exo-terra moss and coconut fiber, soaked with water using 1 tbsp salt for a gallon of water. I also have a container in there also with some moss that is filled with the same water. The first day she buried herself under the moss in the water container, but only stayed maybe a few minutes, before getting out and hanging out in a corner on top of the coconut fiber. With a pair of needle-nosed pliers, I put a couple of big flakes of fish food right in front of her. She took it, tasted it, then pushed it away as if to say "no, I don't want that." Then I gave her a freeze-dried mysis? shrimp plus a couple of freeze dried bloodworms and I did see her eating some of that. Last night, when giving her the same thing she grabbed the pliers, then took the food from them. She has since mainly hung out in the water container on top of the moss in there. I may add one or two small females.

I also bought two pairs of vampire crabs, one "bicolor" pair, the other "red devil", which arrived this morning. Their habitats are set up similar but they have a hiding place as well. They are wild-caught, and they seem a bit scared. Maybe I'll be one of the lucky ones to have these guys survive and produce. I do plan to add some rocks and/or small pieces of driftwood for climbing and hiding places.

Pictures to come later.

[knxtninverts]

Female red claw crab in water/moss

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Male vampire crab, "red devil"

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Female vampire crab, "red devil"

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Male vampire crab, "bicolor"

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[knxtninverts]

Female vampire crab, "bicolor"

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Vampire crab current setup, blue dish has water in it plus Java moss

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And ... mating crabs? Male on top of female, she appears to be upside down ... anyone know the gestation time of vampire crabs?

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I also have a few Thai Micro Crabs, tiny freshwater crabs that live underwater.

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[knxtninverts]

I'm a little confused about the care of these vampire crabs. Some info I found says to add a bit of salt to the water, others say not to (from what I could find before I got them listed add some salt thus the setup with added salt, found more info after getting them that said not to). One site that listed putting salt in the water I think has captive bred crabs. I realize being wild caught they have probably been through a lot and they may not last very long, but I want these little ones to have the best chance of survival.

I AM confident that the red claw crabs do need brackish water, but not sure on the others.

I plan to add plants to their habitats but right now they are in a "basic" setup. Thank you for any and all info.

Update as of Sunday evening: The vampire crabs have been hiding all day, red devils male in hideout, female buried in damp moss; bi-colors male in corner, female half buried in damp moss. I put a small cricket in with the bicolors, and it's still alive 8+ hours later. It's even crawled by the male. I put another cricket in just a few minutes ago to the red devils habitat where the cricket went into the hideout. I lifted the hideout a few minutes later and cricket was still alive, and male took off across the terrarium. The cricket has crawled on top of him. Maybe they (the crabs) need time to settle in. I've put freeze-dried small shrimp and crickets in last night, and know that the male bicolor did at least check it out, and some was gone by the morning. I'm not sure if the red devil's food was touched.

Male Red devil and cricket

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[Mustafa]

I see you are expanding your invert collection. The Geosesarma spp. ("red devil" etc.) do NOT need or want salt at all. They come from wet rain forest habitats far from the sea. I've bred another species of Geosesarma multiple times and I can guarantee you that they never got any salt. I currently have the "red devil" Geosesarma sp. and I can tell you that they need quite a bit of time to settle in and feel comfortable...if they survive of course. As opposed to your red claw Sesarma sp. Geosesarma tend to be more on the cryptic side, staying hidden most of the time. Having said that, my red devils come rushing out of their holes and hiding spots now when I offer them food. They actually eat flake food just fine right off the bat. Some attack it as it falls on the ground as if the flake food is a small insect...others are more timid and wait a little until I close the lid to their tank and move away a little bit. If they are not feeling well, though, they won't eat at all. Just a small tip concerning your setup. The "vampire crabs" and "red devils" (which are not usually called "vampire" by the way) are not usually climbing crabs, so they may have some trouble finding your water container. I would either bury the water container at ground level or change your setup so that your land section taransitions pretty smoothly into your water section. These particular Geosesarma spp. seem to molt in water only (my experience so far anyway) so they may frantically look for water when the time comes. My prior Geosesarma species (Geosesarma notophoroum "Mandarin crab") was completely terrestrial, even molting completely on land.

As for those "micro crabs", I have them, too, and my conclusion is that they have absolutely zero pet potential. Mine have never done anything else but sit on the plants in my aquarium and do absolutely....nothing. You see them move a tiny bit once in a while and that's it. So far nothing much to observe there...and I'm not expecting this to change really. Too bad...the idea of a small, fully aquatic crab is quite appealing.

[knxtninverts]

Thank you for the info. I'll change the setup to have freshwater only. What you can't tell from the picture is that the water container is pretty level to the ground at most points around it. It does look like it is higher. I'll try fish food tonight and see if it's been touched in the morning.

I've had my little micro crabs almost two months. I got 7, and I think they are still 7 in there. And yes, mostly they just sit there hidden in the plants. They are in with dwarf shrimp and I also had dwarf crayfish (CPO's) and baby platies in there, but have since moved the crayfish and fish out into other tanks. One little crayfish, maybe 3/4 inch long, when I first got her/him and put them in there it went after one of the crabs. The crab actually got the crayfish for a bit (and the crayfish learned it's lesson to stay away). But the crabs seem not to move fast and do not seem to "hunt" anything. I have found in the last few weeks one or more will come out when food is given. I have witnessed some activity overnight sometimes when I'm up briefly during the night. I think they are a nocturnal species.

[Mustafa]

I have found in the last few weeks one or more will come out when food is given. I have witnessed some activity overnight sometimes when I'm up briefly during the night. I think they are a nocturnal species.

Possible. Mine don't move around all that much at night either actually. I remember reading somewhere (probably some scientific paper) that this species and similar species live in floating mats of water plants in nature...on their stems and roots. They seem to basically filter out particulate matter with their hairs that are all over the legs and claws. That would make them pretty sessile animals by nature...an unfortunate fact for the human observer.

[knxtninverts]

Another question on the Geosesarma species. How often do I need to change the substrate in their setup? Part of it is damp coconut fiber, somewhat packed like dirt, and the other part is damp "exo-terra forest moss" or similar pet store packaged moss. Plus the water, currently in a container. They like to bury in the moss. My main concern is mold and ammonia/nitrite/waste buildup.

[knxtninverts]

Updates:

My original pair of bicolor crabs passed away a few days after I got them. "Round 2" arrived on Saturday March 31st, 3 pairs of bicolors, 3 pairs red devils, although I'm pretty sure I got 2 red devil females and 4 red devil males, but that is ok, one pair was to replace the bicolors I lost as he sent all the bicolors he had left. At this point I think this will be the last attempt at keeping these, at least that's the plan. One of the male red devils died a couple of days ago but he jumped out of a cup I trying to put him in for a closer look and fell a few inches and died a few hours later. My original female red devil isn't moving much and doubt she'll live much longer. Since the newcomers arrival I lost one of the bicolor females, which was carrying eggs. I'm not sure if she was killed by the male or another female (had 3 females and 1 male in a 10-gallon "habitat"), all I know is she lost 2 legs and then was found dead. Another bicolor female in the same habitat I suspect is carrying eggs and she lost a leg today. I may end up splitting them all up into same sex pairs / small groups and hope one or more females are carrying and live to have their/her babies. Most are still not eating much (having tried freeze dried crickets, FD mealworms, FD small shrimp, FD bloodworms, flake food, small live crickets). I tried small crickets again and between 4 crab habitats a few were eaten.

My original red claw female died as well but I did end up getting 2 more females and they stay hidden all the time under the moss. Their food is mostly eaten on a daily basis.

Updated setup picture: since this picture was taken I added some damp green spagnum (sp) moss around the plants; setups are similar among the habitats, still intend to put a few more plants in there. I will probably take all the moss out as it seems to mold fast. The water containers are plastic sandwich containers, with rocks to climb out on plus some java moss in the water.

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I found this when I came home today -- picture taken from top, red devil female had climbed the plant. She climbed down after the picture was taken.

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I'm still looking for advice on how often (if needed) to change the habitat and/or water. Right now I'm changing the water about every other day. With the intent of taking out the moss and adding plants, I'm thinking only a spot cleaning will be needed (other than changing the water). Any comments/advice would be greatly appreciated.

[Mustafa]

Sorry to hear/read about your losses, but that was to be expected. I lost about 5 of my original 12 (6 pairs) animals, too. That's in less than 12 months. The rest seems to have stabilized. I have an integrated setup with a little water part and a huge land area...both are connected and plants are growing in the land area. In this setup I don't really have to change the water. I just fill up evaporated water with RO/destilled water and have a few calcium carbonate rocks in the water part so the Ph does not nosedive on me. The rocks also provide calcium that the crabs may or may not get out of the water directly. Most, if not all, of their calcium needs are usually fulfilled via the food. I don't think you need to change the water every other day as the crabs are probably not in the water all that often. I think if you put some (live) aquatic moss into your water containers and fill them up with RO water (and some, not too many, carbonate rocks) you can just keep refilling with RO or destilled water once the water evaporates too much. That way you can give that "system" a chance to establish some microorganisms that may take care of possible waste (in addition to the moss).

[knxtninverts]

Another update:

I'm down to 4 bicolor crabs -- 2 pairs in a 10-gallon; and 3 red devils -- 2 females and a male -- also in a (different) 10-gallon setup. I haven't had any losses in a couple of weeks, but am wary of getting my hopes up these will survive long term. One of the bicolor females I believe is carrying eggs (with a very slow progress of her getting a "bigger" belly). They seem fairly lively if I touch them to try to get them to move, but mostly I leave them alone. But ... I still haven't seen much interest in food given. A 1/4" live cricket is eaten occasionally. Sometimes a dead cricket is eaten. Some flake food is eaten by the red devils, not sure on the bicolors. Mainly I've been putting in (wingless) fruit flies, probably 3 - 4 dozen or more, every day, plus a small amount of crushed flake food. I never see any interest though in any of them trying to catch the fruit flies. Some end up in the water container (more so in the bicolors habitat), others likely climb up the sides of the aquarium and escape. I usually see several fruit flies around / eating some of flake food I put in. Occasionally I've put a small live mealworm or two in for them ... often seeing it crawling around the next day, or it just buries itself in the substrate. Other offerings I've tried include freeze-dried food -- shrimp, bloodworms, crickets, mealworms. I don't know how long they can go without food (or not eating as much as they need) ... or maybe I'm worrying too much and they are eating something.

Here's a picture I took a few days ago -- plants are growing nicely in the red devils setup. Here's one of the red devils, plus one is behind a plant further back. One of the females regularly "hides out" up in one of the plants, mostly one of the fern type plants.

red devil crab setup.jpg (203.63 KiB) Viewed 18500 times

The bicolor female who is suspected to be carrying eggs ... I also wonder if she could be in the process of a molt as she looks a bit dry and for the lack of a better term, coming apart as far as the top shell.

Back view:

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Front view:

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[knxtninverts]

Still another update:

Saw a female bicolor eating a mealworm last night -- not the one that is carrying eggs, though. But came home to this tonight:

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After initial alarm, counting crabs I see the one molted. Hopefully the little guy (a male) is alive, I barely touched him and he didn't move at all. This is the first time I've had one of them molt.

[Mustafa]

Thanks for the update again. I really hope that your crabs survive and produce young. Out of the original 12 "red devil" crabs I got at the beginning of march I only have 6 left, also. Mine eat regularly, but they are not big eaters. Your crabs may actually eat a fruit fly here and there and may be done for the day after that. If you miss it, you may think they are not eating at all. If they are healthy they will eat, but they really do not need all that much at all. Keep the updates coming!

[knxtninverts]

Another update:

I'm still having bad luck, it seems. Within a few days of my last update, I not only lost the bicolor male who had molted (he never moved), but the female bicolor that I thought may be carring eggs. Moreover, I lost a red devil female unexpectedly, just found her dead in the terrarium. Just a few days ago I lost my last red devil female apparently due to issues with molting. She was ok for several hours after I had found her molted shell in the water container, even actively moving around, then she made a rapid decline and died by the next afternoon. That leaves me with only a red devil male, plus one pair of bicolors. At this point I do not have plans of getting any more crabs at least in the near future, mainly because I just can't justify spending money on animals that keep dying on me.

In better news, I found the female bicolor molted a few days ago. I think it is safe to say now that she is fine.

My 2 female red claw crabs, BTW, are doing fine as well. I had only seen one for a while, so did a search a couple of days ago, and found both of them in the water container

[Mustafa]

Unfortunately, this is reality with wild-caught animals...they just up and die..more likely than not. The same applies to shrimp. After several months I am down to about 3-4 out of the original 12. I'm also not planning on getting more Geosesarma spp.. I honestly don't think that they are all that interesting for most people, since they hide all day (and apparently most of the night, too) and only come out sporadically to eat. Not a good "pet" if you want to observe them running around, picking at things and interacting.