Best Hermit Crab Enclosure: Tank Size, Materials, and Lid Requirements

A 10-gallon glass tank is the minimum for 1 to 2 adult hermit crabs, with at least 5 additional gallons per extra crab. That means a group of four should be in a 20-gallon or larger enclosure. While that is the minimum, larger tanks are often easier to manage because they hold heat and humidity more steadily and leave room for deeper substrate and enrichment.

Floor space matters more than height alone. Hermit crabs climb, but they also need room for food dishes, fresh and saltwater dishes, extra shells, hides, and molting substrate. If you are choosing between two tanks, the one with a larger footprint is usually more useful than a tall, narrow enclosure.

Glass is usually the best enclosure material for pet hermit crabs because it retains heat and humidity better than many plastic habitats. PetMD specifically prefers glass over plastic for this reason. Standard aquariums and reptile terrariums both work if they are escape-proof and can safely hold deep, damp substrate.

Plastic travel carriers and small novelty habitats are poor long-term choices. They dry out quickly, often do not allow enough substrate depth, and may not provide enough stable floor space. Full mesh enclosures are also a poor fit because they lose humidity too fast. If you already have a screen top, many pet parents switch to a glass lid or partially sealed top after confirming safe airflow and monitoring humidity with a gauge.

A tight-fitting lid is essential. Hermit crabs are skilled climbers and escape artists, but the bigger issue is humidity control. PetMD recommends securing all habitats with a tightly fitting lid, and closed-top systems are generally better for humid species. Without a proper lid, warm moist air escapes quickly, especially in air-conditioned or heated homes.

The ideal lid helps hold humidity while still allowing routine opening for feeding, cleaning, and water changes. Glass lids, fitted acrylic tops, or reptile terrarium lids modified to reduce moisture loss are common options. If condensation is heavy all day, airflow may be too limited or the enclosure may be too wet. If humidity stays low despite misting, the lid is often the first thing to reassess.

A good enclosure is not complete without enough substrate for burrowing and molting. Hermit crabs need a deep, moisture-retentive substrate that holds shape when tunneled. In practice, many experienced keepers aim for at least 6 inches, and deeper is often needed for larger crabs. The tank must be large enough to hold that depth while still leaving room above for climbing structures and safe access.

Inside the enclosure, include hiding spots, climbing decor, and multiple unpainted spare shells. PetMD also recommends two shallow, non-metal, non-porous water dishes: one with fresh dechlorinated water and one with properly prepared saltwater. These features take up more room than many pet parents expect, which is another reason minimum-size tanks can feel crowded quickly.

For most pet hermit crabs, aim for 75°F to 85°F and 70% to 90% humidity. PetMD emphasizes daily humidity monitoring with a hygrometer, and low humidity can become life-threatening. Warmth and humidity work together, so a tank that is warm but dry is still unsafe.

Use a thermometer and hygrometer rather than relying on feel. Enclosures placed near vents, drafty windows, or direct sun can swing too much during the day. A stable room location, a secure lid, deep substrate, and appropriately placed heating equipment usually do more for enclosure success than frequent spraying alone.

A practical starter enclosure for 1 to 2 hermit crabs often costs about $120 to $300 in the United States in 2025-2026, depending on whether you buy new or used and how large you go. A basic 10-gallon aquarium commonly runs around $70 to $90 at major pet retailers, while a 35-gallon reptile terrarium may cost around $190. Add a digital thermometer-hygrometer for about $8 to $13, an under-tank heater for roughly $10 to $40, substrate, dishes, hides, and extra shells, and the total rises quickly.

Going larger at the start often improves husbandry and may reduce the need to upgrade soon. If your budget is tight, ask your vet which enclosure features are most important to prioritize first. In most cases, adequate size, humidity retention, safe heating, and deep substrate matter more than decorative extras.