HCA: Hermit Crab Association

Thanks for all the great info - I’ve been reading your boards for months preparing for my daughter’s Christmas gift of hermies.

Here’s our setup:
-4 tinies, species unknown (we planned for 3 but bought 4 bc I read that many die right after purchase).
-20G glass tank with screen top that’s been siliconed
-temp 76-80, humidity 80-99
-fresh and salt water dishes, changed daily
-fed a mix of fresh foods (nuts, seeds, shrimp, fruit, etc) daily
-one sponge rotated day-on, day-off so it dries out
-second level over 1/3 of the tank accessible by fake chola or coir mat ramp
-terrarium-grade moss
-5-6 extra shells
-6” substrate 1:5 sand:EE
-multiple shelters
-heated by UTH mounted on back wall insulated with tinfoil + folded blanket. Also a blanket on the lid.

Our crabs were visible and active for the first few days we had them. One of them (maybe 2?) changed shells.

For the past few days, we haven’t seen them at all; they’re burrowed down in the sand. We know at least one is alive because we’ve been finding new sand piles and tunnels, but we haven’t seen or heard them. Should we be worried?

Not at all! It’s normal for hermit crabs, especially when you first get them to hide for the first few weeks. If they are digging then they are probably going to molt. If you don’t know about molting there is a care sheet on here but I don’t know how to attach it. If they are molting they can be under for up to a couple months depending on how small they are and as they grow even up to a year or more. They may also just be going under to destress and that could take awhile so you shouldn’t be too worried although sadly it is possible for them to not survive from stress which is really not in your control. I wouldn’t be too worried though about digging, molting, and hiding.

Your tank set up sounds great by the way! The only thing is when you get a chance you should probably add some more shells. Not trying to be rude or anything, just a suggestion! You are doing great and good luck!

Welcome to crabbing and to the HCA!
Sounds like you're off to a great start!
Just a few suggestions if you're open to them...
You don't need to change the water daily, a couple times a week is enough (I'm lazy and only change once a week).
Don't use the sponge in the water at all, it will eventually grow bacteria. You can put it in the time dry, the crabs will sometimes munch on them.
Be sure the crabs have a source of calcium daily, along with the variety you are feeding.
HCA recommends 3 to 5 extra shells per crab. Check out the 'shell's guide to be sure you are offering appropriate types of shells.

Don't be worried at all, many crabs will bury right away. Be patient, they could be de-stressing, molting, or just hanging out down there. Don't worry for at least four months.

Thanks for the suggestions! I have read about molting but thought it would be a big coincidence for all of them to go under at once. I’m reassured by your comments.

Re: sponge - will do!
Re: calcium - we have a cuttlebone, which I think is calcium
Re: shells - added a couple more today and will try to fine more soon (our aquarium supplier was sold out!)

Thanks again. Suggestions are always welcome.

For shells:
Ebay, Amazon, Surprisingly Hobby Lobby in some areas.
Etsy shops i've used are SimplySeashellsDecor and Seafoamgreenco

Everything has been covered, so I'm just here to give a warm welcome. Welcome to HCA!