Look closely at the hermit crab environment and ask questions about the food, bedding, housing and temperature needs for your new pets. If you have never owned hermit crabs before a book on caring for hermit crabs is a wonderful resource. There is a list of hermit crab guides listed under Books to the left. Make sure that you can purchase extra shells from the shop or alternatively from a seashell shop, craft store or tourist shop ( see shells for more information.)
When I am selecting a crab I will ask permission to pick up and handle the hermit crabs. Slowly and gently pick up any available crabs from the tank and fluidly lower them onto your palm, stretched flat. It is important that you keep your hand flat as most hermit crabs see you as a giant and are afraid you will drop them! Considering the ease with which they fall I think that they are justified in this fear. You need to be ready at all times to catch them in case they tumble off your hand.
Watch each crab as it meanders across your palm. Sometimes it takes a while for a crab to loose its initial fear of you and peek out from the safety of its shell. Try to keep your hand still and talk soothingly to your crab, always remembering to place your empty hand alongside the other at the edge the crab is crawling towards.
Examine each crab closely for factors of ill health, such as:
Does the tank have a strong, fishy smell...(something like two day old fish sitting in the sun)
Are there any flies, pests or mites on the hermit crab or inside the enclosure?
Are there fungus or mould spots on the hermit crab?
Has the crab lost more than one limb?
Is the crab overly inactive?
Does the crab seem aggressive?
Is the shell too large or too small for the crab?
If this is not your first crab will it be a good match for your other wards?
Do you have suitable-sized shells for your new ward
Does it have both chelipeds(grasping claws)?
Do you want a small crab, suitable for handling by smaller children, or do you want a larger crab?
Crabs are Dead or Moulting
A strong fishy smell could mean that the hermit crab has passed on or is in the middle of a moult. It is best to avoid crabs which are moulting when purchasing a new pet as such crabs as it usually ends in heartache because of the stress on an already weakened crab. If possible, ask the pet store to make an isolation unit within the tank, perhaps a 1/2Gallon/2Litre Small Pals Living World Deluxe tank filled with sand/coral sand/fine river pebbles or T-Rex CalciSand® that is slightly moistened and with the lid closed so that the other hermit crabs cannot bother the moulter. For more information, visit my moulting page
Flies, Pests and Larvae
Sometimes you may find bad conditions in Pet Stores, mainly incorrect bedding such as wood shavings, coconut bark, kitty litter, aquarium gravel, cedar shavings and the like. Hermit Crabs can only survive if there is adequate humidity and sanitary conditions. Some pests are attracted to the bedding and because it is difficult to see the pests clearly, this type of substrate can be a haven for them. Hermit Crabs are stressed easily, and the presence of mites and other parasites such as fly larvae and even mould/bacteria can be enough to severely stress the hermit crab to fatality. Some species of flies will lay their larvae on weak hermit crabs, with the larvae eating through the flesh and slowly feasting on your helpless hermit crab. Moulting hermit crabs seem to be targeted, perhaps because of the almost sweet smell that some newly moulted hermit crabs can have. Some people describe it as a silicone glue smell, others as a sweeter smell. This is the hardening of the new tissues with the help of chitin and other chemicals, and in their vulnurable, inactive state they can do little to ward off the parasitic attackers. It is important to use some type of fly screen gauze over the ventilated parts of your tank if flies become a problem.
Mould/Mold, Fungus and Bacteria
As with improper bedding/substrate, mould and bacteria can build up in crabitats that are over humid without sufficient airflow, or those that are not cleaned at least monthly. If you see mould or fungus spots on the hermit crabs, it is important NOT to take them home and introduce them to your colony UNLESS you spend time treating the infected hermit crabs. Mould and Fungus can spread in the right conditions, and lead to contamination between your helpless pets.
To treat mould and fungus spots or infection, gently bathe the hermit crab in approximately one half (1/2) of a teaspoon of aquarium salt(Instant Ocean or Doc Fishwell are the best or Pure Sea Salt – never table salt) to a quart/Litre of dechlorinated water. To this saline solution, it may be recommended to a drop of StressCoat by Aquarium Pharmaceuticals (or another brand if available). It has been proven that a dip in a saltwater or saline solution can deter the growth of mould or fungus on several types of fish [reference] and the presence of the aloe vera in the Stress Coat will help to act as ‘nature’s bandage’ in this case and help to reverse any damage done by the saltwater at this strength. The normal solution is half as strong, only 1/4 of a teaspoon of Instant Ocean/Doc Fishwell type Aquarium Salt per quart/Litre. This may not cure the problem but it will treat it if performed on an ongoing basis. It is another reason to keep a salt pond with the above saline solution within the tank since it can help prevent such maladies.
Inactivity or stiffness
It is important to make sure that the hermit crab you buy is active and healthy, otherwise, an inexperienced person may buy a dead hermit crab, which has happened on occasion. Pet Stores may suggest that the hermit crab is inactive or sleeping due to land hermit crabs being nocturnal creatures, but most hermit crabs will stir unless they are in a comatose state or in one of the stages of moulting. Remember to wait at least a minute to determine this and then watch the crab after you lower it back to the tank. If the hermit crab is stiff or does not react to being brushed inside the cheliped (grasping claw) with a piece of paper or hair, AND/OR being placed on a flat surface with any people present standing away so that there is no movement or shadows, AND/OR there is no antennae (feeler) movement at all, I would leave the hermit crab for a while and look at the other hermit crabs. Activity and friendliness are usually signs of health and vigour.
If you are new to land hermit crabs as pets or do not have the set-up to create an isolation section to your crabarium, it is probably best to try to avoid crabs that bully or attack the other crabs. Aggression is rare but it can bring turmoil to a happy crabarium. I have had the very disturbing misfortune to come home from a day of teaching to find a hermit crab torn apart by a new tank mate either for the shell or during displays of aggression to assert pecking order/territoriality. It takes forever for them to settle down and ‘play nice’ and may only end if the aggressor is attacked while in a vulnerable condition (eg. during a moult). If you do adopt an aggressive hermit, make sure you separate it from the rest of its tank mates for a time and give it access to as many shells as possible before adding to the crabarium. If you cannot separate them, make sure to create a hiding space or dividing wall and keep a close eye on them. A lot of the time hermit crabs that are aggressive were the victim of aggressive attacks themselves, and they may be very anxious, scared hermit crabs. Once they feel secure within their new environment, you will usually find that the hermit crab will change shells or spend a lot of time hiding out in the hide spots, especially the VERY wonderful Hagen Ornamentalls Rock Cave that hermit crabs flock to.
Shell Fit and Selection
It is important that you have a choice of shells for your new wards around the same size as they are already in. Some crabs spend months in the same shell and refuse to budge, despite the fact they sorely need to. Try and buy some shells to go with the hermit crab at the same time, or as soon as possible, especially if there is a lack of suitable shells in the pet store’s tank. If you don’t have a good range of shells, try and choose a shell that is in a well-fitting shell. Look for signs such as: can the hermit crab retract deep within the shell when needed; does the cheliped and walking leg block the entrance if another hermit crab tried to pull him/her from the shell; is the shell chipped or cracked in a place that could cause a leak of shell water and dehydrate the crab; does the hermit crab have trouble carrying the shell on its back, or hanging loosely within. If you can provide a home with shells for these misfortunate hermit crabs, I am sure they will be very thankful to you for your generosity, but if you cannot, it can mean that the hermit crab will stay in such inappropriate shells until you can, which is not fair on them and may cause fatality in the long or short term.