HCA: Hermit Crab Association

Hey there! I'm having an issue with mold, but first I will give you some background...

I was given a hermit crab about a month ago (my first), and the tank was bone dry, with one water dish, less than an inch of substrate, and store-bought crab pellets. After doing some research, I decided to overhaul his tank. I added a block of coconut husk (about 2 - 2 1/2 inches deep now), made the entire substrate damp, added a saltwater bowl, started feeding him fresh food, added some decorations and climbing stuff, etc. After I did all of this, I found out that it is very unhealthy for the crab to go straight from low humidity to high humidity. My bad. I was a little worried, but it's all good now it seems.

After a day or so, my crab burrowed in the substrate, which I expected him to do. He was under the surface for upwards of 3 weeks. While was submerged, mold started growing all through the tank, against the glass in the substrate, anywhere on the surface where the moisture was trapped, etc (I'm guessing this was caused by the old substrate that I added to?). I wanted to clean it out and replace all of the substrate with new stuff, but he was still submerged and I didn't want to disturb him.

Now he is out and about, but only at night, and he is very shy. When he first came, he would sit on my palm, and walk from hand to hand. Now, as soon as he see us coming to the tank, he burrows again. He comes up to eat and drink, but other than that, we don't see him out of the substrate.

My question is this - do I take him out, replace the substrate in it's entirety, clean the tank, etc., and risk stressing him out again, or leave the moldy substrate in the tank for another week or two and hope that he feels more comfortable before I start stressing him out again?

Which is more dangerous - the mold, or the stress that I may cause him?

Thanks a bunch! Like I said, this is my first Hermie, so I don't have much of a clue.

On a side note, I don't have a heater because I have not been able to afford one yet, and I don't have a thermometer. I do have a hygrometer, and humidity is sitting just under 85% right now (it got up to between 90 and 95% at it's highest). He is in a ten gallon tank, by himself, although I plan on adding another hermie on my next paycheck. He has a halved coconut shell for cover, but he chooses to burrow rather than enter it. I'm using Wardley Chlorout for my fresh water (approx. 1 drop to every 1 1/4 liter) and HBH Hermit Crab Salt for my saltwater (approx 1 teaspoon for 1 cup of water). If you have any tips, they would be appreciated!

Since he is coming out at night I would replace the substrate. It's not really known how dangerous mold is for hermits, but it certainly is unhealthy for us humans to be around! If he hasn't molted yet (and he may have since he disappeared for three weeks) then it's best to get the substrate changed now before he disappears for another month. It's certainly important to get the tank clean before adding another hermit as the new guy will most probably molt soon as well. The mold is probably from the old substrate, but it could also be from cocofiber that is too wet or from lack of airflow in the tank. It can be very had to find that right mix of having the tank sealed up for the right humidity while still maintaining enough air flow to keep everything from getting moldy and stale. Mold can be hard to get rid of when it's on objects - I've boiled cocohuts and baskets and still had it come back so strong to the point where I just had to throw them out, so when you put the tank back together keep a close eye on everything and pull things at the first sign of mold.

The temperature gage and, if you need it, a heat source is important. Temperatures too cool will stress them out and cause problems. Ideal temp for these guys is around 80 degrees during the day, which in most cases is warmer than what our houses are. The thermometer doesn't have to be fancy or even from the pet store - for the past year and half I've been using a $8 digital thermometer/hygrometer from Walmart.

Also, the salt mix you're currently using isn't strong enough for long-term use. Hermit crab salt is sodium chloride and calcium carbonate, while what they really need a mixture that replicates sea water and all the elements (50+ depending on the brand) that are in it. You can find these types of marine salt mixes in the salt-water fish section of the pet store. You'll get more for your money, and your hermits will be healthier! Common brand names are Instant Ocean, Oceanic, Red Sea, Kent, Coralife, and there are many more.

Thanks a bunch! I will change out the substrate very shortly. The problem shouldn't be with airflow, since I do not have the tank covered at all. The humidity still has no problem staying right up there, so hopefully the hygrometer is functioning properly. I bought it new, so I expect that it would be. When I bought it, I chose it over the temp gage because I thought it would be more crucial to be able to measure the humidity. I had to choose one or the other. I will hopefully be going out and getting more supplies tonight or tomorrow.

Thanks for the tip about the salt - I'm currently using the stuff that came with the crab, but I figured that I would probably need to replace it since it seems that everything that is made specifically for crabs doesn't actually suit crabs all that well... Ha ha...

Thanks for the advice! i will let you know how he is doing once I've cleaned the tank and he's had time to settle in.

Well, I did a thorough cleaning of the tank last night, replaced the coarse coco husk substrate with finer plantation soil, which is also all coco husk (the only reason I went finer is because it was cheaper). I grabbed a temp gage, but don't have a heater yet because they are so darn expensive up here in Canada. So I'm going to order one over the internet - any suggestions for good sites? I found http://www.hermitcrabpatch.com. Way cheaper! $12 versus $30... A little unfortunate shipping to Canada, but not too bad. I also got another crab, but he's tiny! My first crab has a min 1" shell opening, and the new crab has a 1/2" shell, and when he closes shop you can barely see him he's so far back lol... The first thing I did was order smaller shells, and some large ones for the big guy. We picked up a shell from the pet store for him (the largest they carried) and he climbed in - he wasn't even able to get his eyes into the shell... Haha, the pet stores around here are so poorly equipped. I will post pics of the crabitat soonish.