HCA: Hermit Crab Association

I just put my new crab in my tank after soaking him and I saw the new guy on top of my old one, and trying to get inside his shell. I immediately separated them and my old one literally RAN AWAY and is currently soaking. New one is looking at other shells. I tried getting the new guy to change shells by putting him in a glass with a damp towel over it..he didn't change. What's happening? How can I make this stop?

It is probably a shell fight. It might help to get some more shells.

Rinse your empty shells in salt water to try and get him interested in them. I’ve had to take one of my crabs out and put her in my spare 10gal for a little time out for a few days. The one I had to isolate was also a new crab that was going after one I have had. I even got the chance to give her the shell I thought she wanted bc my original crab had changed out of it, but the other still didn’t change. She never did change shells but she must have had some time to think about it because I haven’t had a problem since. Lol.

I had the same thing happen when I added a rescue crab to my tank. One of my original guys grabbed the new one from behind. I heard chirping from the new one and quickly separated them. Then he went after the same crab again. I added a few new shells after dipping them in salt water and the attacked changed into a new shell in a few minutes. That was back in January and haven't had any issues since.

As Riniky said adding shells soaked in saltwater helps entice crabs looking for new shells. Be sure you have a large variety of different types and sizes since crabs can be very picky when it comes to selecting new shells. Be sure the shells are the proper size for the crabs. I have had pretty good luck ordering shells with openings 1/8" to 1/4" larger than what they are currently wearing with shell openings 1" and smaller. I always like to get two or three shells the same size. They look the same to us but crabs are super picky and can pick out very slight size and weight differences in them. It's recommended to have a minimum of 3-5 shells per crab in you tank at all times. It's even better if you have additional shells so you can change out for a different selection every few weeks. Even pulling shells out of the tank, cleaning them in salt water, and putting them in different locations helps.

Here is a link to the attack I caught on my cam. You can see near the end of the video when I saw what wad going on then finally broke it up.
https://youtu.be/zHibTLJxYmQ