Mysterious crab always buried

[Makyu]

Hi, I'm new to this place! I've had my crabs since last August now, and there's one question that I've had for a while. While one of my crabs is very active, healthy and seems overall happy, the other one will stay buried for months and then mysteriously come up for 2 or 3 days only to bury again. In the time I've had my Jeckyll and Hyde, Jeckyll has only been spotted on 2 separate occasions and never for more than 3 days. Being a night owl myself, I'm pretty sure he doesn't come up at night either. Both crabs are medium-sized.

So, tank conditions; my two indos are my first enclosure-kept pets. When I first got them I got advice from my reptile-invested friend (surely he knew how to build a habitat, right?), but he didn't know too much about hermit crabs so with time I figured out that the conditions I kept them in weren't optimal, though they did work -somewhat- if I kept a close eye on the temperature and humidity and made adjustments where needed.
The temperature was mostly even, around 25°C all the time, though the humidity has had a lot of fluctuations and could be 80 one day, and then 40 the next (followed by a lot of panicked misting by inexperienced me). I also had a fruit fly problem later on. The substrate was full coco peat, and because the enclosure was one of those terrariums with doors at the front, I had to make a height gradient where my substrate depth only reached proper depth at the back of the tank. In this sub-optimal tank, I know Jeckyll has successfully completed at least one molt, since he lost a leg and regrew it later on. The only other time he came up was to swap out his shell, and then he went under again.

About 3 weeks ago, I introduced them to a new crabitat out of an old 40gal aquarium. The substrate is now proper 5:1 with more than enough depth. The humidity is consistently at 99, and temperature consistently at 27°C. I no longer mist either. There are many hides and climbing opportunities, many plastic plants, and a hamster wheel. Cuttlebone and "regular" food are at different spots in the tank to encourage exploration and plenty of shells are present. While their old water bowls worked fine, I've opted to change them for deeper bowls anyways.

Even now, Jeckyll has buried instantly and hasn't come out since. Could it be that he's molting again, because the proper substrate depth is 'more inviting' for it? Could there still be something I'm still missing? Or could he just enjoy "doing nothing underground" more than being above ground?

[hermitcrablover2]

Jeckyll (Jeckyll and Hyde are really good names for hermit crabs by the way ) might just be hanging out underground. It's not uncommon for hermit crabs to stay under for months at a time, even if they're not molting. Depending on his size, it's a good idea to let him stay under for at least 6 months, because if he's molting you don't want to disturb him. Also for your hermit crabs's food, the cuttlebone and some normal hermit crab food is good, but you also need a source of protein and varied foods. I know lots of hermit crabs like meats and fish, some bugs, worm casting, peanut butter, honey, and other strange delicious (to the hermit crabs) food

[curlysister]

It could be any of those scenarios! They dig to molt, to de-stress, and sometimes just because! LOL. But when crabs are small, they molt very frequently - so sometimes it might seem that they are underground way more than they are above.

[Makyu]

Jeckyll (Jeckyll and Hyde are really good names for hermit crabs by the way ) might just be hanging out underground. It's not uncommon for hermit crabs to stay under for months at a time, even if they're not molting. Depending on his size, it's a good idea to let him stay under for at least 6 months, because if he's molting you don't want to disturb him. Also for your hermit crabs's food, the cuttlebone and some normal hermit crab food is good, but you also need a source of protein and varied foods. I know lots of hermit crabs like meats and fish, some bugs, worm casting, peanut butter, honey, and other strange delicious (to the hermit crabs) food

Thank so much for your reply, I'm relieved! I named them after their personalities, since Jeckyll is quite modest and very shy and adorable, whereas Hyde is a bit of a crazy crab, prone to hanging out in weird places, likes to walk the wheel backwards sometimes(???), has odd shell choices, is absolutely fearless and has tons of entertaining adventures throughout the tank
I should've clarified, by normal crab foods I did also mean to include meats/fish, bugs, honey etc. Though peanut butter is a new one for me, so thank you for the recommendation! I suppose it would have to be unsalted peanut butter, like the one filled with mealworms you can get for birds in the winter, right?

[hermitcrablover2]

I'm not 100% sure about the peanut butter, I'm pretty sure you can give them normal peanut butter, I'm not sure if it has to be unsalted or not.. I think the bird peanut butter would be good too because mealworms are also nutritious food for hermit crabs