HCA: Hermit Crab Association

Hello, I have had my pet hermit crabs for about a year now and I am concerned about one of them.

I had one of my hermits pass away about 3 weeks ago. I discovered her under a sponge without a shell, turned dark grey and curled as if dead for a week, not pale or showed any signs of molting. I was confident she was dead because she tried this before and was not molting at all, but I couldn't save her this time. One of my other crabs is now giving me mixed signals of molting or dead and I am not sure what she is trying to do, and I don't wanna lose her too so anyone who can help please do so!

My two living crabs left are named Crabby and Patty. My deceased one was named Krusty (yes a spongebob them lol). Crabby molted 6 months ago under the substrate and was very successful, doubled in size and everything. He is still active and healthy so I am pretty sure it is not the tank causing issues for Patty. Patty started giving signs of molting for 2 weeks, becoming paler, staying near the water bowl, and no longer fitting in her shell.

To my surprise, though, she surface molted! I placed a barrier around her and kept her secluded from Crabby as he is double her size now and I didn't want her to be disturbed. I did slightly move her so I could protect her better, and at the time she was about to fall out of her shell. However I left her alone for 2 weeks and now I am concerned because there has been little change.

She is now not coming out of her shell (which is a good thing I guess?) but she is completely white except her big claw being purple. Her eyes are no longer glossy and kinda look sucked in. Her attenea no longer moves and her body is completely petrified. I did the smell test and she smelled fishy but like how the tank smells, not rotten and I need to be closer to her to smell her fishy smell. And yes I was able to smell her because I had I move her again. Why I moved her is because Crabby went underneath the substrate to get to the sea fan (he is crazy sometimes lol) and caused Patty to roll out of the protective barrier, hence why I needed to move her again. I know it's not recommended to move them, but if I hadn't I was worried she wouldn't be safe during her molting phase, if she is molting.

I have tried reading on whether her symptoms are normal or not but no one is giving clear answers! I keep reading mixed advice: smell is dead but not, movement is good and not, etc. We are in week 3 and I am hoping I can get some sign she is alive because I have no clue. If someone has experienced these symptoms of molting (no movement or sign of life, slight smell but not terrible, petrified body, etc.) or knows what is going on, please tell me.

Crabby's molt was so different because he moved during his entire molting. He came up frequently for water and would move throughout the stages, but with Patty she is so still. Thanks for any advice, stay safe!

Hello, i can understand your concern. If Crabby came up during his “molt“ then i do not think he was actually molting he may have just been digging to relieve stress. As for Patty I am not sure. So little research has been done on hermit crabs it’s just hard to know. Patty could be experiencing something due to change in conditions in the crabitat. Could you tell me more about your current setup, temp, humidity, water pools and food? I would love to help you in any way i can. Have a great night!

It sounds like she’s passed away.

The fact that she surface molted means there’s something wrong, either she didn’t think she could burrow or she’s ill or injured to begin with.


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More than one surface molt most likely means something is wrong with the substrate, such that they cannot burrow to molt normally. Because molting is necessary for their survival, this can eventually become a deadly situation.

You need a proper kind of substrate (many crabbers use a mixture of Eco Earth or similar substrate and play sand--NOT "calci-sand," which is potentially hazardous for hermit crabs). The substrate needs to be at least two times as deep as your largest crab, preferably more if your tank will allow that, and it needs to be "sand castle moist"--so that, if you put a finger down in the substrate, when you take your finger out, the hole your finger made stays well formed. It is important that water not be pooling at the bottom; just moist substrate all the way through.

Take a look at the general "crab care sheets" as well and compare them to what your set-up provides. The fact is that none of us has a "perfect" set-up, and we can always improve their conditions somewhat. Best wishes!