HCA: Hermit Crab Association

I have 4 crabs 3 of them went down with in weeks of each other it's been about two to three weeks since my one pp named ray came up. I have tride to introduce the crab that didn't molt(cha) in those weeks and ray but cha seems to be agressive or at least I think he is. If anyone knows about crab behavior with other crabs after molt or tips to introduce them after molt that would be very appreciated.

Unless the molters had been moved to a separate tank or the non-molter was relocated when the others went under, there should be no need to re-introduce the crabs. If the non-molter is acting aggressively, it could be that the newly-molted crab still smells "tasty." A quick dip in the FW pool for all crabs concerned should help remove any "you smell different" scent.