HCA: Hermit Crab Association

JoeHermits wrote: ↑

Tue Feb 04, 2025 9:49 pm

The drop in humidity could certainly be a factor, so it may be good to check the plastic wrap and see if it’s sealing properly

JoeHermits wrote: ↑

Tue Feb 04, 2025 9:49 pm

Getting dug up is likely also a factor if she did just molt. If you think she was molting and the exoskeleton is indeed hers she should be kept separate from the others and allowed to eat it. A plastic food container kept in the tank will do in a pinch

C: ClareCrabOwner :) wrote: ↑

Tue Feb 04, 2025 7:16 pm

Since you've come to the emergency forum, we know you want a fast answer to your question. In order for us to figure out the problem as quickly as possible, we ask that you answer the following questions as best you can. Some of them may seem odd, but they're all designed to give us the information we need to give you a good solution for your problem. The things in the [ brackets ] are there to make this post easier to read once submitted. Thanks!


1. What kind of substrate is used in your tank and how deep is it?
I have a mix of subsrate from a friend who got it for me. I'm not sure what all is in it, it looks like a mixture of sand, coco fiber, and something else. I baked it in the oven @350 for 30 minutes, to kill any bacteria/other stuff that might be bad for them. I also added some coco fiber. It is about 3, maybe 4 inches deep? I'm not completely sure, it might be a little deeper. Both tanks are about the same depth.
do you have any idea what the other component is? Just want to make sure that it is not calcium sand. Depth should be 6 inches or 3 times the height of your crabs, which ever is deeper.

2. Do you have gauges in the tank to measure temperature and humidity? If so, where are they located and what temperature and humidity do they usually read?
I have a tempurature/humidity guage. I move it around the tank from time to time, because I have 2 ten gallon tanks and only one gauge. I will get another one soon! Tank 1 usually measures 99% humidity and 69-75 degrees (Farenheit). Tank 2 usually measures 70% and 75-85 degrees.
defineteky need to make sure that the first tank stays above 75, 69 is too cold.

3. Is a heat source used in the tank? If so, what?
Tank 1 has a heating pad on each of the short sides of the tank, that stops at the soil line. Tank 2 has an overhead light, with a daytime bulb that provides light and heat, and a nighttime heat-only bulb. Sometimes turn on the nighttime bulb to heat up the tank more during the day (both lights on).
You should probably acquire a heat mat for them, because the heat lamps can dry out their gills.
4. What types of water are available (fresh or salt) and how is the water treated (what brands of dechlorinator or salt mix and what ratio is used to mix it)?
Both tanks have fresh water and salt water. We have a well, so there is no chloride in the water. The fresh water is untreated. The salt water is made with salt from the pet store for hermit crabs. I'm not sure what brand it is: the bottle is labled "tropical." One teaspoon of salt is added to 1 cup of water.
Tank 1 has a freshwater dish about the size of a phone, and is deep enough for the crabs to submerge themselves in. The salt water dish is about half that size. Tank 2 has a large water dish, that takes up about 2/5 of the tank's suface area. It is deep enough for the crabs to submerge themselves. The salt water dish is a seashell. I had to use a large water dish to keep the humidity up in this tank!
for the salt, you need to get marine salt. Something like instant ocean. Cheaper and better. Salt labeled for hermit crabs does not have the minerals they need.
5. What kinds of food do you feed and how often is it replaced?
I feed the commercial foods I got from the pet store when I'm busy, but I usually feed them a variety of fruits/veggies/other foods. I usually feed them each evening and take out any uneaten food in the morning.
Have you made sure the crab food is not toxic to feed yet? You can look at the commercial foods caresheet foe more info.
6. How long have you had the crab and what species is it, if known?
I have had the crabs for about 3 weeks. They are Purple Pinchers.

7. Has your crab molted, and how long ago did it happen?
One of the crabs molted, about 2 weeks ago. I think it was Crystal, but none of the crabs were next to the exoskeleton, so I'm not sure. Nobody ate the exo, but I left it in there.

8. What type of housing are the crabs kept in, what size is it and what kind of lid is on the housing?
Both tanks are 10 gallon aquariums. Tank 1 has a plastic aquarium lid, like the kind you use for fish. It had a couple holes I duct taped over. Tank 2 has a wire mesh lid, with plastic wrap over the lid, except for under the light.

9. How many crabs are in the tank and about how large are they?
Three crabs in tank 1; two crabs in tank 2. They are probably about small crabs??? Maybe a little bigger or smaller. They are all almost the same size.

10. How many extra shells are usually kept in the tank, if any?
I have about a dozen extra shells total, and 10 more coming in the mail. Most of the ones I have are two big/small. Am going to get more soon!
I rotate the shells between the tanks.

11. Have there been any fumes or chemicals near the crabitat recently?
No. Well, we do have a diffuser we add essential oils to in the same room. I don't think that would bother them.
I don't know if that would hurt them, but I would stay on the side of caution and make sure it can't get to them.
12. How often do you clean the tank and how?
I've only had the crabs for a little while, and have not needed to clean the tank. Would appreiciate suggustions on how best to do so, and how often.
I usually just spot clean.
13. Are sponges used in the water dish? If so, how are they cleaned?
I don't have any yet, but I have ordered some for their dish that will be here later this week. I plan on rotating the sponges regularly, rinsing them, allowing them to dry, then microwaving them between uses (Because I've read they could build up bacteria if just left there).
Like you said sponges just build up bacteria, and there is really no point to having them. They don't help the crabs drink abd they barely increase humidity,.( you can put a moss pit in to help instead). You can put them dry in food bowl or on substrate for the crabs to have a snack though.
14. Has anything new been added to your crabitat recently?
The crabs, And everything else

15. Is there any other information you would like to share that might be helpful (anything that is regularly part of your crab care, playtime, bathing, etc.)?
Playtime? I plan to eventually (in several months, to give the crabs time to settle in) handfeed the crabs and maybe let them explore around the house.
Baths? Not any yet, would like advice on how often to bath and what to bath in (water w/ stress coat, regualar water, or salt water).
Do not bathe your crabs it just stresses them out and messes the water they keep in their shells up.
I got 5 crabs from Pet Smart/Pet Supplies Plus. Most seem to be doing well. I gave one to each of my siblings to name, and they have not decided on names yet. I named mine Marine and Crystal. I noticed Crystal appeared to have trouble pulling her shell around, because she walked very slowly. Or maybe she was just shy and waiting till I left!

To make a long story short, I got more things to put in the crab cage and had to dig them up a couple times, because I didn't want to squash their burrows. One of the times I dug them up, I noticed one had molted. I think it was Crystal, but I'm not completely sure...
I have two tanks, as noted above. Crystal was in the tank with higher humidity/lower tempurature, and she hadn't moved from the same spot in the middle of the cage for a day or two, so I put her in the tank with lower humidity/higher tempuratures, because I thought maybe she was to cold?
You shouldn't dig your crabs up unless in an emergency. Just put things on top of your substrate with weight evenly distributed.
16. Please describe the emergency situation in detail.
This morning I looked in the cage, and saw a hermit crab sitting in the water dish without any shell on! I looked around, and spotted Crystal's shell near my pile of extra shells. I wasn't sure what to do, so I decided to run up to the pet store and try to find a couple shells her size. I thoaght she grew out of her shell and didn't like any of the other shells, so maybe she'd like some of the others. The ones at the pet store are almost $5 each! I knew I could order cheaper ones that size online, so I only got 2. On the way home, I realized one had a hole in it!
While, I got home and found that Crystal had gone back into her shell. Maybe she saw it was day time and decide she'd be safer in that shell and it was better than nothing?
Becuase Crystal was in the water dish when I found her, I thought maybe it was not humid enough for her, so I put her back into the more humid/less hot cage.
when a crab leaves its shell, it means that there is something seriously wrong with the environment. If a crab is healthy, they would rather be ripped in half than leave their shell, even if it is too tiny. They will die without their shells. They know this. Please take my advice and mak these changes to their environment. I would also consider getting a bigger tank, just so they have some more room for activities.
Oh, by the way, I have no idea if the crabs are boys or girls. I just refer to Marine as a boy and Crystal as a girl because I didn't want to write "it."

So, what I made this post for was to find out why Crystal left her shell, and if she is likely to do so again. Is there anything I can do to minimize this possibility?
follow my suggestions above.