Setting up an Isolation Tank for molting
Every crab owner needs to have a Isolation Tank, or ISO, on hand. Not only does it provide an enviroment for molting if that is your chosen method, but it should be used as housing for newly purchased crabs. The size of the ISO depends on the size of your hermit crabs. Small crabs only need about 6 inches of substrate, while jumbo crabs need a 10 gal tank with 12 inches or more of substrate. The crab needs enough room to dig down and create a subterranean cave. It also needs room to spread out and push off its exoskeleton. The ideal container for a ISO is a glass tank or aquarium. If your main tank is large enough to place a small plastic ISO inside of it, that is acceptable. Your ISO will need an overhead light also to maintain a normal cycle of light and dark.
Type of tank:
- A glass tank ranging from 2.5 gallons to 10 gallons with a lid
- A plastic Kritter Keeper with Saran Wrap on the lid
- A plastic bucket or bowl with a lid, vent or puncture to allow air exchange

Gauges needed:
- Hygrometer
- Thermometer
Types of lid:
- Glass
- Acrylic/Plexiglass
- Screen lid with Saran Wrap

Types of substrate:
- Playsand
- Forest bedding/Eco Earth
- Mixture of the two
Type of heater:
- Under the tank heater for a glass tank
- Plastic containers can’t be heated, which makes them a poor choice for a ISO unless you can place them within your main tank, or find a room that is warm enough to keep the ISO warm also.
ISO temperature should be between 75-80F This should be the substrate temperature not the air temperature. The humidity should be 75-80% Relative. Don’t guess, get the gauges! Place them close to the substrate surface because that is where the crab is going to be, not at the top. Offer food and water until the crab digs down. After that it is unnecessary until it surfaces. Gently smooth the surface of the substrate so you will know if your crab comes up. ISO's should be placed somewhere quiet. But a normal cycle of light and dark should be maintained. Light is critical to a crabs ability to metabolize and this is how a hermit crab regulates it's body.
Signs your crab is ready to molt:
- Digging
- Consuming large amounts of water or soaking in the dish
- Cloudy Eyes
- Ashy looking exo
- Lethargy (very in active)
- Spilling water to dampen the substrate
