I had recently purchased some gold claw crabs. They came from a brackish tank. My tank is also brackish. This afternoon I noticed one crab was almost dead. the others seem to be doing fine. Scavenging and climbing all over everything. The only other fish in the tank are guppies and a pleco. Now am I doing something wrong or are crabs sensitive to changes in environment? Like switching from tank to tank. I would like to replace it but don't want to loose another one. Please if anyone has info about these crabs let me know. Thanks.