There are a few signs that will tell you if your crab is actually going to molt.
First off- Digging. This will be a sign if the temperature and moisture in your aquarium is fine. If it’s too hot or too cold, the crab might be digging to avoid the habitat he does not like, so check your gauges first.
Is your crab getting unusually lazy, is he losing interest in everything that is going on around him? That might be another sign of molting.
If you notice small nubs on places where your crabs lost limbs used to be, you can get ready for molting. Hermit crabs grow back their limbs when preparing for molting. The small nub looks like clear gel.
Finally, if your crab gets an extremely big appetite and gets a small black bubble of fat on his abdomen, under the fifth pair of legs, this might mean he is going to molt. He needs the reserves to stay alive while he is molting underground. It might be hard to spot the rise in appetite, because your hermit crabs might prefer to eat and drink at night, while you’re asleep.
These are the signs of crab molting, but don’t get excited if you spotted one sign, there should be at least few of them on a getting ready for molting crab.
When is the question
A lot of crab owners get worried if their crab does not molt at least once in a year, but do not worry, some crabs might molt only once in 18 months. Smaller crabs might molt more frequently. Bigger crabs might stay in sand after molting for a month.
Molting crab care
The best help you can do for your molting crab is leaving him alone. Let Mother Nature take care of him. Do not try such things like tearing the skin of your crab; this might cause limb loss and other skin problems. When your crab molts, don’t bathe the weak, soft crab under water, this will increase the chanced of all types of bacteria attacking him. Do not try to dig the crab up, this might mean your crabs death.
Left over skin
When the molting is done, you don’t have to throw away the leftover skin. Your crab will eat it. And yes, that is very healthy to him. Hermit crab left over skin is full of calcium and chitin, just the things he needs to harden his exoskeleton.