HCA: Hermit Crab Association

Since you've come to the emergency forum, we know you want a fast answer to your question. In order for us to figure out the problem as quickly as possible, we ask that you answer the following questions as best you can. Some of them may seem odd, but they're all designed to give us the information...

6 months ago I bought 3 crabs, one large, one small and one medium. I kept in a 80 x 48 x 50cm terrarium, 6 inches of substrate (playsand mixed with coco fibre). They have both fresh and salt water, I heated it and sprayed it to keep humidity up and fed them food from hermiesdelights.com.au. Soon af...