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?
50/50 play sand and coconut fiber. 8” all around. Always sandcastle consistency!
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 one hydrometer, across from the 2 UTHs mounted on the back of the tank. It currently reads 95% humidity and 80 degrees F. I never let the temp and humidity go below 80. It’s almost always higher than that, and stable.
3. Is a heat source used in the tank? If so, what? 2 UTHs as mentioned, placed above the substrate level.
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)?
FW and SW are both provided in dishes deep enough for Kai to submerge herself in and get out safely. Each is treated with SeaChem Prime. I use Instant Ocean for the SW, mixed according to the directions on the box.
5. What kinds of food do you feed and how often is it replaced?
Ooof. I feed a variety of foods. Protein such as bloodworms, anchovies, shrimp, crickets, mealworms. Organic vegetables and fruits. Spirulina, dulse, kelp, eggs, eggshells, cuttlebone, urchin.
I always provide leaf litter and chia throughout the tank. I try to hit all aspects of the crabbie food pyramid. I replace the food once a week, since I give enough to where she revisits throughout the week before I replace it with a new set of ingredients.
6. How long have you had the crab and what species is it, if known?
I’ve had Kai since Aug 14, 2017. She’s a PP
7. Has your crab molted, and how long ago did it happen?
From what I have documented, the last molt was from around Dec. 1 2019-Jan. 10 2020.
8. What type of housing are the crabs kept in, what size is it and what kind of lid is on the housing?
29 Gal tank, with a plastic hood. The large openings have been completely sealed off to keep from humidity escaping. Smaller openings have mesh to allow airflow.
9. How many crabs are in the tank and about how large are they?
Only 1. She’s about medium size. When I got her she was super tiny!
10. How many extra shells are usually kept in the tank, if any?
Well over a dozen. Most of them are turbos.
11. Have there been any fumes or chemicals near the crabitat recently?
Nope.
12. How often do you clean the tank and how?
I spot clean every week. That’s about it. The most I do is rewet the sand with dechlorinated FW and remix if I find that the sub is losing sand castle consistency- which is not often at all.
13. Are sponges used in the water dish? If so, how are they cleaned?
Nope.
14. Has anything new been added to your crabitat recently?
Nope.
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.)?
Even though Kai is the only tank resident, she has always shown good health, and hasn’t shown any different behaviors since her tank mate passed away a long time ago. She’s always appeared happy, healthy, and very active. I also don’t handle my crabs.
There aren’t any signs of flooding or bacterial blooms. The mushroom invasion I had a while back is over, too.
16. Please describe the emergency situation in detail.
So here’s what’s happened. About a week or two ago, I noticed that Kai switched from her too-small turbo to the only land snail shell in the tank. She’s never paid any mind to it, so I found the switch very odd. She been more quiet and hide-y than usual, too. Fast forward to yesterday. I checked up on her and noticed that the snail shell was empty and in front of the coconut hut. I peeked in the coconut hut, and behold, Kai was there, shell-less. I went into fight or flight mode, scooped her up gently with the coconut hut she was under, and managed to ease the shell back on with no issues. I should have probably bathed her, but I have to admit, the the water pools weren’t clean- I was not a good crabbie parent and missed the routine replacement of the water dishes- so they were dirty for some time
Well, once I managed to get the shell back on, I placed her in the empty Kritter Keeper I had with some clean FW and SW. I bathed her then, and she even drank some water. I left her be to rest, but noticed that something else was wrong. While she is startled by my movements, she doesn’t retract fully into her shell, lets her eyes drop down, and isn’t defensive with her claw either. She hangs out half out of the shell. She looks awkward and heavy, as if it’s hard to move around at all. Often times she’ll look as if she’s tilted or leaning over, as if she’s injured or too weak to stand upright. Eventually she makes her way back to normal resting position (upright) but won’t move for a long period of time before making any small movements. I gave her a mix of honey, spirulina, high protein mix, and cuttlebone. Fortunately she ate some. I left her be in the KK and put the whole thing in the main tank for the night.
In the morning I took her out of the KK and put her back in the main tank, but she was the same. Looking weak, not moving much, etc. She ate more of the mix I made, but hasn’t moved from the spot I put her in. Not long ago, I put her next to the refreshed water dishes to see if she would drink. She went for it, but fell in a bit. She tried to get out but it was almost like she didn’t have the energy to do so. Next thing you know she’s leaning so far out of the shell I’m convinced she’s going to ditch it in attempt to get out- so I gently moved her out myself.
I’m not sure what else to do. I’m pretty worried that maybe I’m doing something wrong, and I don’t want to add more stress to her. All of these symptoms make me think that she’s way over-due for a molt, and it’s taking a toll.
Her stillness is truly anxiety inducing, especially when she looks weak and injured the way she does. Thoughts? What else can I do? Sorry this was so long. Just wanted to make sure I give as much info as possible. Thank you so much for any help!
There are incorrect shells to buy. Here is the shell guide: 
I'm really worried
