CALCBIOME — LAND HERMIT CRABS

What tank for your hermit crabs?

Minimum tank size, substrate depth for molting, spare shells and water: calculated from the number and size of your crabs.

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Your crabs

Volume: at least 38 L (10 gallons) per small or medium crab and 57 L (15 gallons) per large crab. Bigger is better.
Substrate: 5 parts sand to 1 part coco fibre, damp like sandcastle sand, at least 3× the height of the largest crab (15 cm minimum).
Water: one pool of dechlorinated fresh water and one of marine salt water, with an easy way out.
Climate: 24–29 °C and 70–80% humidity.
Shells: 3–5 natural spare shells per crab, in assorted sizes.

Crabs	Size	Tank	Substrate
2	Small	76 L	15 cm
3	Medium	114 L	15 cm
4	Medium	152 L	15 cm
3	Large	171 L	20 cm
4	Jumbo	228 L	21 cm

These are minimums recommended by keeper associations and vets.

Minimum volume (L) = number of crabs (at least 2) × 38 L for small or medium crabs, × 57 L for large or jumbo (10 and 15 gallons per crab).
Example tank: the smallest common size (76 × 30 × 33 cm, 91 × 46 × 40 cm…) whose volume reaches that minimum.
Substrate depth (cm) = 3 × height of the largest crab, at least 15 cm (20 cm for large crabs).
Substrate litres = tank floor area × depth, split 5 parts sand to 1 part coco fibre.
Shells = 3–5 per crab.

3 medium crabs, the largest 3 cm tall: 114 L minimum (for example 91 × 46 × 40 cm), 15 cm of substrate, about 63 L, and 9 to 15 spare shells.

At least 76 L for 2 small or medium crabs, and 114 L for 2 large ones. Bigger is always better.

At least 3× the height of the largest crab, and never less than 15 cm: they bury to molt.

No: they are social animals, keep at least 2.

Yes: one pool of dechlorinated fresh water and one of marine salt water made with marine aquarium salt, never table salt.

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