Several marine species of hermit crabs are common in the marine aquarium trade. Of the approximately 15 terrestrial species in the world, the following are commonly kept as pets: Caribbean hermit crab, Coenobita clypeatus, and the Ecuadorian hermit crab, Coenobita compressus. Other species such as Coenobita brevamanus, Coenobita rugosus, Coenobita perlatus or Coenobita cavipes are less common but growing in availability and popularity as pets. Hermit crabs also require certain specifications to be able to thrive well as pets. The list is as follows:
· Humidity gauges (humidity: 75-85% relative)
· Temperature gauges (temperature: 70-75°F)
· Substrate: sand, coconut fiber (must be deep and diggable for moulting)
· Minimum of a 5 gallon tank for one crab; and 10 gallon tank for about 20 crabs
· Shells (shells are changed during growth)
· Fresh water dish
· Salt water pool for submerging (aquarium salt)
These omnivorous or herbivorous species can be seen as useful in the household aquarium as scavengers, because they eat algae and debris. Hermit crabs were once thought to be "throwaway pet" that would only live a few months, but with proper care can thrive for many years. For example, Coenobita clypeatus is commonly listed as having a 23 year lifespan if properly cared for , and some have lived longer than 32 years . .
In general, and despite their moniker, hermit crabs are social animals that do best when kept in groups . They also require a temperature and humidity controlled environment, and an adequate depth of substrate to allow them to dig while moulting.