HCA: Hermit Crab Association

I want to start off by saying my crabs are currently in a safe environment with safe substrate, but
I think I have some bad substrate and I’m wondering if it can be tested for toxins/noxious substances, fumes or whatever. This involves 2 crabs and 3 tanks, one of which I think had the bad substrate. They came to me in a 4gal tank which was setup all wrong. They’ve been in a 15 gal tank with recommended setup per this group for 9 months. Recently purchased a 45 gal tank with the recommended setup, but I think something is wrong with the substrate. In general the setups are basically identical except where noted.

1. What kind of substrate is used in your tank and how deep is it?
Eco Earth and Play Sand 6” deep (Identical for both tanks except made from different containers/batches purchased aprox 9 months apart.
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?
Two in each tank about 3” below top of tank 1 in front of tank 1 in back. 80-95% humidity. Temp 75 – 80. I had trouble keeping temp up in 45 g tank and wrapped it in blankets.
3. Is a heat source used in the tank? If so, what?
Heat mats attached to back of tanks.
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)?
Dechlorinated fresh and salt water bowls. Tetra BettaSafe Water Conditioner and Instant Ocean
5. What kinds of food do you feed and how often is it replaced?
Variety of fresh and packaged food all are on the safe lists. Changed every day.
6. How long have you had the crab and what species is it, if known?
Purple Pincher I’ve had for 9 months
7. Has your crab molted, and how long ago did it happen?
Crabs have molted twice in the 9 months I’ve had them last time was about 2 months ago.
8. What type of housing are the crabs kept in, what size is it and what kind of lid is on the housing?
15 gal for 9 months then for a short time 45 gal both with glass lids.
9. How many crabs are in the tank and about how large are they?
Two ¾ shell openings
10. How many extra shells are usually kept in the tank, if any?
6-10
11. Have there been any fumes or chemicals near the crabitat recently?
Not that I am aware of, but I believe the substrate in the 45g tank is contaminated in some way.
12. How often do you clean the tank and how?
I do very little cleaning of the tank as springtails are a great cleanup crew. I do remove old food and clean and rotate food dishes. I change water bowls about every 2 weeks. I’ve never seen poop – thanks springtails.
13. Are sponges used in the water dish? If so, how are they cleaned?
No
14. Has anything new been added to your crabitat recently?
New 45 gal tank set up with exercise wheel and new Egg crate wall on the back.
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.)?
Before use Eco Earth was broken up with Chlorinated water.
15 gal tank 9 months ago wet Ecco was mixed with sand and crabs put in immediately
45 gal 1 month ago Ecco left to air and dry before mixed with sand. Crabs were put in 2 weeks later. Both tanks have hides etc. Both tanks were purchased used, clean with vinegar and baking soda and rinsed with Chlorinated water. They were put in the 15 gal immediately. I let the 45 gallon tank sit for 2 days before putting anything in it.
16. Please describe the emergency situation in detail.
My Crabs have lived in a 15g tank since shortly after I got them. I decided to get them a better environment hence the setup of a 45g tank.

When I moved them to the 45g they were crazy active and started running around and climbing almost immediately. They seemed a little stressed, but I thought it was the move to a new environment. The 45g tank had egg crate on the back wall they did not have this in the 15 g tank. They were climbing on the wall and even around the top perimeter of the tank like crazy. . I felt guilty that I hadn’t given them a wall sooner. They even slept on the top of the wall with their legs wrapped tightly around it. After a full day and 2 nights in the tank, the behavior started to concern me. I was having trouble keeping the temp of the tank high enough and decided to move them back to their 15g tank until I could get the temp right. I thought maybe they were clinging at the top because it was warmer. Before I moved them back, I put egg crate on the back wall of the 15g tank because they seemed to like climbing so much but they haven’t used it in the 2 weeks they’ve been back there.

Yesterday I had a water leak and substrate got much to wet in the 15 gal. I took out about ½ the wet substrate and added in dry substrate from the 45g tank and mixed them together. Then I put the crabs back in. Nothing else changed in the tank. I checked on them 10 minutes later they were both clinging to the top of the egg crate (climbed for the first time in that tank). Alarm bells went off in my head and I pulled them out of the 15g tank.

They are currently in a 4g tank that I quickly set up with about 2” of leftover “uncontaminated” substrate from the 15g tank. I also put egg crate on the back wall of this tank which they have not climbed at all. They ate and drank last night and are resting.

Soooo – I think something contaminated the substrate in the 45g and I want to determine what and how before I do much more. Is there a way to test the substrate for ammonia or something else noxious?
Both the good and the bad substrate was made with the same brand of play sand from different bags purchased at Lowes. They also had Eco Earth purchased from 2 different sources. So the contents should have been the same but from different batches. I still have 2 bricks of the same Eco Earth used in the 45g tank, but I’m afraid to use them. I’m of course concerned that their gills have been damaged and they are probably stressed from all of the recent changes, so I’d like to let them rest before stressing them again.

To clarify, the substrate doesn't had a bad smell or bad color?
You are thinking there is something wrong with the substrate because they climbed up to the top of the egg crate in both tanks to avoid the sub, correct?

Curly sister,
Yes I cannot smell or see anything wrong with the substrate. I’m concerned because they stayed at the top of the 45g tank day and night for the whole time they were in the new tank first wildly moving around then just hanging there. If I moved them to the substrate to eat or drink they quickly crawled back up. I moved them back to the old 15g tank primarily because I was having temperature problems and wanted to sort it out without them. They did not climb while in the 15g tank until I mixed in substrate from the 45g tank and then they were hanging for dear life at the top of that tank. When I moved them to the 4g tank they settled down and there has been no climbing. I should add that they are much more subdued and less active since they were in the 45g tank. Before now they would come out to watch me cook or do dishes etc. I hardly ever handled them but they’d take food and new shells from me and seemed to be quite trusting. I attributed there anti-social inactive behavior to them not trusting me anymore. Now I’m concerned they were poisoned in someway. Food and water have not changed. They are currently eating and drinking but mostly sleeping together in the hide. I’ve ordered ammonia test strips for aquarium and thought I’ll try testing water thick with each substrate.

Ps thanks for responding.

I totally get your concern, but if nothing is visibly wrong with the substrate or nothing smells wrong then it is most likely fine. The weird behavior could honestly just be them finding a new favorite spot, or that they feel their preferred way to destress is to climb. I’m not an expert but that would at least be my best guess.


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Crabs like to climb, and many of mine sleep as high up as they can get. It's probably just that it's a new tank and they now have the option to do that. If you aren't smelling anything wrong and the substrate you bought was clean and dry with nothing worrisome, I really wouldn't be worried about them. It sounds normal.

I want to thank everyone for their response. Hopefully I'm just a nervous mom. Ya don't EVEN want to talk to me while they're molting. I can't believe how much these guys have stolen my heart.

If you're that concerned, can you just scrap all of the old sub and replace with new? It seems like cheap insurance.

Mood - that’s my plan it’s just all too weird.

Have you considered temperature? You temperature seems fine in the tank but it might be to cold or hot in the substrate it's self. If your house is cool (like below 70-75) then the sub might be cold for them or if they are close to (or on) to a heater then it might be too hot.