Keeping a Halloween Moon Crab alive

Moon CrabNB: in the 4 years since I wrote this article, Wikipedia has gotten some updated info that might prove useful to new owners. If you have a crab that looks like the one in the picture, check out the Halloween Crab article; if you have a darker-bluish crab, try the Moon Crab page.

After the recent purchase of our second Halloween Moon Crab (or whatever they’re called–it’s ambiguous), Zero Two, the little bastard died. Now, the original Zero was in a sorry state when he arrived in our house, missing three legs, and then soon four. When he keeled over, two weeks into his stay, we were saddened but not overly surprised. At the All New England Reptile Expo, we got a much healthier looking specimen, who seemed to be much more energetic, burying in the sand at night and eating frequently. Unfortunately, the place was so busy they didn’t want to talk to me about an $8 crab, so I couldn’t get any decent (better) advice on his care and feeding.

Then, one day, after we lost power for a few hours, I returned home to feed the fire, only to find Zero Two dead. I figured the cold must have killed him, but it was only down to about 60 degrees in my house, and I found that to be pretty reasonable for Costa Rica (their native habitat, according to at least a few sites (1, 2)) on a relatively cold night.

Upon closer inspection of all the information about moon crabs online (which, like most reptile and exotic info, is always contradictory), it seems that they are a seaside-dwelling creature that needs access to both fresh and salt water. This surprised me, since the first pet store we’d gotten Zero from had called him an ‘African Land Crab,’ but had mentioned that he could also be called a moon crab. PetSmart’s care sheet for African Land Crabs definitely doesn’t jive with the other two pages mentioned earlier, so I’m now thoroughly confused. Either way, I’m planning on getting another moon crab once I’ve gotten a generator for power outages, and I plan to sculpt some sort of hybrid land-water tank, rather than a mostly sand substrate with a water dish. Any information anyone might have about owning one of these critters would be greatly appreciated–I don’t want to kill another one.

halloween crab, moon crab, halloween moon crab, african land crab, enclosure, new england reptile expo, crab care


  1. Ralph Heasty says:

    I have had a halloween crab for over a year now he is in a 30 gallon terrarium with 3" of water in one end and the majority of the tank with 2" of potting soil planted with small house plants replenished as needed he eats sporadically of the plants but seems to like pet grass, ferns, and spike moss best. he burrows into the soil.and only comes out at night, so I rarely see him.

  2. lauren says:

    halloween crabs and moon crabs are different

    moon crabs are from africa. halloween crabs from peru area.

    that picture is that of a haloween crab

  3. lace says:

    they need to be able to submerge themselves in the water. (fyi crabs have gills) it wasnt cold that killed him, it could of been stress or the lack of water. i found it best to just throw some feeder goldfish in the water part of the tank so you dont have to worry about keeping them fed, and they keep the little fella amused because spends all day 'hunting them' and if he isnt a good hunter hell eat the leftover fish flakes.

    my carb has been doing for over a year now without anything special, just tap water sand and fish flakes, and the occasional gold fish.

  4. vanessa says:

    moi mon crabe est mort d'un facon bizarre je l'ai trouver mort un matin avec la carapace ouverte comme si quelqu'un avait peser dessus. j'aime savoir pourquoi il était comme sa le pire un jours avant il était super en forme

  5. Erika says:

    We've had our crab for almost two years. He's in a 10 gallon tank with about 3 gallons of water, and 2 inches of gravel covering the bottom of the tank. He has a log and castle (bought at Wal Mart) to climb on so he can get up out of the water, and we have a tank heater to keep the temperature comfortable for him. We feed him brine shrimp and shrimp pellets…..thinking about trying some fruits and veggies after reading about it online. We did have him in a 20 gallon tank with our fish but after he ate 3 of them we thought he deserved a tank of his own. Also, when we bought him from the store, he was one of a pair…..about a month later we were down to one crab….they really are territorial. He's very active and somewhat playful through the glass, although we don't actually touch him. One issue that has popped up within the last week is that he's developed a hole in the triangle on his underside. We don't know what it is, but hope he will molt again soon and have a fresh start. If anyone has info to share, we'd really apprecaite it.

  6. Lorraine Kurpis says:

    I purchased two crabs one week ago and find everything confusing. At the reptile show where I purchased them, they were called moon crabs. They are just like the picture: Haloween Crabs. I was told they will eat anything because they are scavengers. I have fed them a variety of chopped veg & fruits (cabbage, carrots, banana, sunflower seeds, apples, even popped corn) They attacked the apple and seemed to love it. They ate all the other stuff while I was not watching. I also put live crickets in with them but, I don't know if they ate them. I was told to put salt in their water. I have been so confused about their environment that I have been trying different things. First I put a bowl of salt water on top of calcium sand with rocks to climb on in both the water and sand. They seemed happy with that. Then I put a plant in organic soil in with them and they dug and hid under the roots unplanting it. Now I have 4" fresh water (w/filter), underwater heater, airrator to add oxygen in the water and create humity, a large bowl with the calcium sand, a lucky bamboo in a vase with stones and rocks of varying sizes. I have noticed they stay underwater for long periods of time and love climbing to the top of the bamboo. The food scraps are on a small plate in the large bowl of sand and it disappears. The main thing I've noticed is they love getting into tight places: between the bowl/glass or behind / between rocks in both the water and sand. I no longer have the salt water in with them. Does anyone out there know if anything I am doing is bad for them. Is the salt water a must? I also took out the organic dirt / plant.

    • Vasken says:

      @Lorraine Kurpis,

      Thanks for your comment on my blog. I got similarly vague advice from the people at the reptile show where I bought my crab, and sadly it died a few months later. I just approved another comment (posted right before yours) that seems to give some good care advice from someone who's been successful keeping the crabs alive. Would you mind also posting the name of the vendor from whom you bought the crab on the blog? I usually find that people at the reptile shows really do a good job with the animals they sell, but I feel like I got bogus care advice (and species identification to boot) from the vendor I bought mine from too. I would mention who they were, but I can't remember the name (it was a few years ago now).

      Thanks, and good luck with your new pet!

      • Chester says:

        I have had my Halloween crab for about a week and a half now. How ever i have hermit crabs 8 purple pinchers and 1 Indonesian. I have had these guys for over a year now. 3 of wich are huge. They live in a 55 gal terarium with 2 levels the bottom being coconut fiber. This will work for the Halloween crab but not the best. Beach/play sand is ideal, reason being they spend most daytime hours hiding and in a nature its underground. Up to four feet down! So be sure to have enough for him to bury his self. Temp. Should range around 82 to 87 ferenhight. And 70 to 80 percent humidity. You can get a hygrometer and thermometer 2 in 1 at Walmart for about 8 bucks its digital. Do not feed the crab anything with preservatives as it will kill him. They are highly "allergic" to metals wich will kill aswell. Raw fish is an amazing treat for these guys. Im not sure on the salt water thing yet. Cant seem to find it but my hermies would prob die with out it… They have 1 gal of fresh and 1 gal of salt. The Halloween crab does and will molt so if he is very lethargic and slightly whiteish those are good signs just leave him alone till Hes done. For the larger hermies it can take up to 8 weeks so he might be gone for a while. Just keep putting food out and fresh water and leave him alone stress will kill these guys. They may look tough but they are very sensitive. Im not sure if you can train them to be able to hold or not… I havent tried Hes kind of intimidating. And very fast. Oh btw i got mind for pet supplies plus and they didnt know anything about him.

  7. jessica says:

    Im only a teenager girl that has a project to do and it has to be on crabs oh my word!!!

    I hate crabs as it is

  8. ali says:

    ok so i had a similar exoerience, after just 2 days of getting this thing. anyway, i am looking to replace it, anyone know where in NY u could find this crab?

  9. Gaby S. says:

    I also got a Halloween Crab from a reptile expo and the people who ran the stand couldn't tell me much about the bugger. As soon as I got home I looked up information about him. I haven't put any salt water in his tank but i've been giving him meat every week in hope thats a good source of salt. I got him in the Pomona Reptile Expo in Aug. and he is quite alive and active for my first crab. Seems like everyone else just got the worst luck with their own.

  10. Chris says:

    I held mine on a pretty regular basis. She never pinched hard, only steadying herself with her claws. She also seemed to like having her back scratched.

    • Jess says:

      They DEFINITELY like having their backs scratched! They throw up their defenses at first, but once you start scratching they settle in, and sometimes even move into it, like they’re saying “more!”

  11. Kitty says:

    I have four halloween moon crabs. They don't seem to like to burrow though. Two got into a fight. One lost his leg and one lost her claw. I just hope that they can molt soon so that they can move normally again. It's harder for the one who lost her claw to eat these days.. Since they don't really burrow, I gave her a mug to stay in, by the water dish.

    I feed them popcorn and lettuce. Their favourite is popcorn kernels because it's spongey and soft and not heavy to carry around. At one point, some of the crabs were hugging a kernel in one claw and munching on another kernel using their other kernel. I really need to get more calcium into their diet though. I tried crickets, but they were terrified of those jumping creatures. They were stuck huddling together in corners for weeks because of the crickets. It wasn't until the crickets stopped chirping and started dying off that they felt free to roam again. I tried giving them canned crickets, but they only tried it once and then they never touched them again. How can I get calcium into their diets? Egg-shells? I found that they don't like to munch on hard textured things…

    • kittygoesmeow says:

      Halloween moon crabs are a bit territorial.. tho they can live in small communities.. with just a few in a tank… as long as your tank is large enough for them to crawl around and hide from each other when threatened. Hermit crabs and halloween moon crab needs are different. One requires a bit of salt.. another doesn't.

  12. PoupouMichaud says:

    Je suis un technicien en santé animal,j’ai gardé et reproduis plusieurd espèces de reptiles et mon premier achat était un crabe halloween.Ces crabes ont vraiment besoins d’humidité et même la preuve j’ai chauffé mon auto et le temps de 10 minutes à l’air sec et le crabe était tous sec,mort et ils se démantibulais complètement.Alors tjrs avoir un bon taux humidité donc si lampe chauffante trop forte elle va peut=être assècher le vivarium donc le substrats dois être humide et vaporiser l’air.Attention eau du robinet donc chlor,chloramine et métaux lords sont toxiques pour les invertébrés alors bonne chance

  13. Carol says:

    I bought two Halloween crabs at flea market in Oct 2011. They hid most of the time and I couldn’t tell for the longest that they were eating the commercial diet that they sold me. I put in several fresh items that they never touched. Finally, the smaller of the two died. He seemed perfectly fine, but just dead one day. After he died, the larger one (they told me was a female ?) has become much more active. She will hide for about a week at a time, digging down under the sand. She seems to do this if I sprinkle some water onto the sand that it drains down and makes it more damp. After hiding for a week at a time, about once a month, or so, she will come out and be active. I have her in a 10 gal glass tank with play sand in the bottom. I have some rocks for her to climb on (but she never does, she will just hide behind them) and regularly put in fresh leafy branches that I snap off plants in my yard. She really gets really active after I add new plant material and I think it’s because of the added humidity and more natural atomosphere. I have three clear plastic bowls that I bury a little into the sand- a smaller one for food, and two larger ones for water. In one, I keep fresh bottled water (room temp) and in the other I mix in hermit crab salt. She will submerge herself in both regularly. She drinks and submerges in the fresh water one more often, but she does like the salt water.
    This morning she molted for the first time. She scared me to death because I wasn’t prepared for how this looks. I took many pictures if anyone is interested in seeing them. At first, I thought she died, but I was surprised because she has been more active and in the water (both fresh and salty) more than usual, so I guess she needed this extra moisture for molting. She has also been eating more than usual. She has been moltin now for about 5.5 hours and seems very tired. Her new legs are out and she moves them, her back shell has sprung up, and her new claws are under her. Her new skin/ shell is pink and soft (her back is still dark though). She is face-down in the sand with her legs wiggling in the air, but she still seems to be stuck in the new shell, somewhere around her mouth area. I am concerned because as quickly as this started, legs out and shell off, I would have thought she would be done by now. She has all of her legs- many posts I read said that after molting, they were missing one set of legs. I would bet this is a lack of large water source (salt and fresh) for submersion.

  14. Charlotte says:

    Care Sheet – Halloween Crab
    Scientific name Gecarcinus quadratus
    Habitat Caribbean and Central America woody habitats, tropical coasts of America at the Pacific and Atlantic
    Size Up to 7 cm (2.755”)
    Life Expectancy Up to 10 years
    Reproduction No reports about breeding in captivity.
    Temperature Between 23-28°C (73.4 – 82.4°F).
    Humidity 70-90%
    Lighting Halogen Sun Mini in combination with the Exo Terra Glow Light reflector is sufficient as heat and light source.
    Substrate The best option is to divide the tank into two zones. One with Sand and the other with moist Jungle Bedding forest bark and moss.
    Décor Terrarium of the appropriate size. Important are two flat water bowls. One should be filled with a water calcium mix and the other should be a mix of water and sea salt, so that the animals can satisfy their needs of regaining salt and lost minerals. Only Marine salt as used for marine aquariums should be used and mixed in accordance with the instructions to the correct mix. Both water bowls should be replenished with fresh water and marine water as the crabs easily foul the water. Plenty of hiding places should be available.
    Terrarium Size From 80 (31.5”) x40 (15.75”) x40 (15.75”) cm for a group of 2-3 animals
    Food Omnivores. Leaves, vegetables, fruit, fish, live food, dry food such as pellets.
    Comment Halloween crabs can be kept in larger groups. Therefore additional hiding places should exist, such as flat cork or small caves. The crabs like digging so allow them at least 2” substrate depth.

  15. matt says:

    i just bought two a day and a half a part and one is waayy bigger then the other. today i woke up and checked on them and the smaller one is missing his right arm. i think a batlle wound from the night before. will he/she b ok? will the arm grow back? will my crabs get along or do they hate each other? any help would b awesome i have spent some time on the net looking but this is the only page that seems to offer any help whatsoever. thanks 😉

    • Vasken says:


      My best advice would be to read through the comments here–some people seem to have some really good advice about keeping these things alive, especially when it comes to temperature (really high) and substrate (sand, etc). Unfortunately, mine died several years ago, so I’m probably no help 🙁

  16. Renee says:

    I bought two Halloween crabs on-line about a month ago for my grandson who is 13. So far I don’ see them much, they both pretty much burrow into the sand and stay there. We have been feeding them lettuce, zucchini, tomatoes, carrots and some fruits. Half their tank is water and the other half is a sandy hill. There is a heating pad under the tank to keep the water at a comfy temperature, and a plant or two. Not having picked them up yet, now we’re scared to. Has anyone heard of placing a cuddle bone in the tank for them?

  17. jen says:

    I have had a halloween crab for about 6 months. Half of the tank is regular water with floating plants ( which he ate on a regular basis) and the other side is burrowing dirt. He is semi active or was. The last couple of days he has been sitting in a corner he does not normally go to and he hasn’t moved one bit, not even if I touch him. I thought he may of died but is he getting ready to molt? I can’t tell and don’t know how to telll. I would hate to toss him if he is just getting ready to molt. Any advice?

  18. Vanessa says:

    I have a Halloween crab from Costa Rica, named her after her birth place, Montezuma. Not sure how old she was when we got her (2009) but seems bigger to me. We keep her by herself in a 10 gallon tank. Initially with tropical plants and two water bowls but she destroys the plants and covers the bowl with substrate— she rearranges her burrows very frequently. Her underground tunnels are crazy. At night she is most active sometimes making a lot of noise (crescent moon?) — after several days of activity she would hide for weeks— we always get scared thinking she us dead… I have dug her out — but there she is upset I disturbed her. Now I just let her be. Foodwise, she eats organic fruits and vegetables, raw chicken and fish, loves BBQ ribs… Hermit food (sometimes), she really likes Spring Mix… Funny, when (if) she comes out of her hiding spots , she watches TV. We enjoy her very much!!

  19. Evonne Maxwell says:

    I just bought a crab today. I don’t know if it is Halloween or Moon. A girl as far as i have read, but not sure of that as well. I named it ‘The Kraken’ cause it looks like a mystical thing to me. Just wondering how i can tell which type The Kraken might be. He/she is almost all orange with a black, back shell. No blue or purple coloring. I hope it’s a healthy one.

  20. Kat says:

    Hi there,
    I know this thread is outdated but I was hoping to get some answers on Halloween crabs. We were assured where we got them they were simple to take care of and got a free small hermit crab with him. We truly love crabs in my family but have never owned one. We fell in love with the Halloween crab. After research, there are so many different contradicting care plans and what they need.
    It seems like from what I’ve read substrate is important. Is it okay to use actual sand from a beach? How deep does the substrate need to be? What is the best materials for a substrate ?

    Do they need half the tank water and half substrate ?

    What temp do they need?

    Do they need salt water dish?


  21. Kitcat76 says:

    Thank you for all the very informative information. There is not a lot online or in stores. Frustrating. But reading through the comments it gives us a better go to.

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