HCA: Hermit Crab Association

A month ago we got our first hermit crab (a purple pincher). We wanted to see how it went before getting a second one (a mistake in hindsight). Our first seemed to be doing well and settled into a routine, so we got a second one a week ago. We isolated for a few days, and the first night the original crab was very interested in the isolation tank, checking all sides for over an hour. Then for the first time ever he buried underground. We assumed he was going to molt, but he has been coming up every night. They mostly get along - the original climbed on new one at one point so I opened the lid and they separated. Since they have done some face to face interactions but mostly are fine. This morning the new crab refused to move off the hole so the original crab couldn’t go underground. Now original crab is in the coconut hide slightly dug in.

Do I need to do anything? Even if I move the new crab and put the original crab over the hole he’s probably asleep for the day anyway…

Welcome to crabbing and to the forum!
If your substrate is moistened to sand castle consistency, the crab could simply dig a hole somewhere else if it wants to go underground.

For sure, I was just wondering if he had been working on a cave to molt and now has to start over. And if this is normal behavior from the new crab or I should be worried? There are many extra shells in the tank (10 gal) which should all be around the right size, which they keep checking out but never changing…is that a concern?

Sounds like pretty normal crab behavior to me.

Ok great, thanks so much!