After that I isolated my original crab in fear that he would kill my new crab for the shell. How long should I isolate my original crab? Or is this something that can't be fixed (as in he'll always want the shell back)?
Just some other info: My new crab fits really well in the shell, yet my original crab does not at all. Yet he still insists in going in it. I'm not sure if my original crab is happy in the shell he is in now, or if he still wants the other shell.
Any tips and advice is very much appreciated

Thank you!