[header] How to care for hermit crabs [title] Make sure you get the right size of tank. [step] A ten or twenty gallon tank is good for two to four small hermits. A twenty to forty gallon tank is good for a dozen small or three to four large hermits. 
Hermit crabs are social animals and should have at least two other crabs with them. The proper home for your crabs should be one that holds in humidity, but still lets in fresh air.