Your main tank should never be smaller than 38 litres (10 gallons) and can hold up to three small hermit crabs. Ideally you should give each hermit crab roughly 11.4 litres (3 gallons) of room. For example, if you wanted to keep eight hermit crabs, then you should probably buy a 91 litre (24 gallon) tank or larger. Buy the biggest possible tank your room can fit.
Why do I need a lid on the tank?
The lid not only helps prevent your hermit crabs from escaping, but also helps hold in heat and humidity as long as it is made of glass. The glass lid should cover most of the tank, but it must also allow adequate air flow in and out of the tank to help reduce the likelihood of mould growth. If your hermit crabs can climb through the air gaps, you can put a mesh lid under or above the glass lid. You can find such lids in reptile stores.
Should I keep my new hermit crabs in total darkness?
Only at night. The tank should be exposed to small amounts of sunlight during daytime. Do not bake the tank in sunlight; otherwise the humidity will drop sharply. Keep a hidey cave in the tank so that your hermit crabs can still stay in the dark if they wish.
Why should I consider buying a second tank?
The second tank is often referred to as an isolation tank. It may be used to separate certain hermit crabs away from the others, such as those who were newly adopted, moulting or victims of a shell fight. You can control the temperature and humidity of the isolation tank for your newly adopted hermit crabs (see the next section) without affecting the other hermit crabs in your main tank.
How big should the isolation tank be?
The isolation tank can be smaller than 38 litres (10 gallons) as long as you still have room to put three dishes and a hidey cave. Hermit crabs should always have access to fresh water, salt water and food, even if they are in the isolation tank.