One of the most anxiety causing issues among crabbers is molting. Crabs grow by molting their exoskeleton and growing a new one. The exoskeleton is made of the same type of material as fingernails; it is tough and used to protect the crab in addition to the shell. While a crab is molting it is very vulnerable to other crabs in the cage who might decide to become cannibalistic and have the molter for a snack. The exoskeleton is very high in nutrients and therefore desirable to other crabs. Since the molter cannot fight off any danger, they need protection. It wise that a smaller version of the main tank be set up and used as an isolation cage for molting crabs, one per cage. If an isolation container is not available, one can be fashioned from a two-liter pop bottle. With the bottom cut off a rinsed two-liter bottle, push it over where the crab that wants to molt is, be sure to push it all the way down to the floor of the cage. By doing this, the molting crab is protected. Be sure to provide the molter with all necessary food and water.
Some signs that a crab is ready to molt include, but are not limited to:
increased appetite
increased water consumption
increased digging
Although these are good signs that the crab should be isolated from its tank mates, they are not always accurate. Crabs are individuals; they will differ in their preferences. Some crabs will molt right on the surface of the cage, however, most prefer to dig into the sand. Some crabs will molt almost overnight, while others seem to take months to finish. The most important thing to remember is do not disturb a crab that is in the process of molting, this is a very stressful time and bothering them now could cause death.
When a crab finishes molting, it will come out of its hiding place. The crab may be a noticeably brighter color and will have black toenail tips on its feet. The newly molted crab should stay in isolation until it is eating and acting normally. When it is ready for reintroduction to its tank mates, it will need bathing. Bathing a hermit crab is an easy procedure; place enough room temperature water in a plastic container to cover the largest crab. Let them walk around for a couple of minutes, too long and they will drown. Bathing the new molted crab with the others will ensure that they smell the same to each other, making the molter less likely to be a victim of hungry crabs.