Hermit crabs are popular pets that are relatively easy to care for. One of the most important things you need to provide for pet hermit crabs is an appropriately sized habitat. When keeping multiple hermit crabs together, it’s essential to give them enough room to thrive.
Quick Answer
The general rule of thumb is that each hermit crab needs at least 2-3 gallons of space. So for 3 hermit crabs, you’ll need a tank that provides 6-9 gallons of space. A 10 gallon tank is usually recommended as the minimum size for 3 hermit crabs.
Tank Size Guidelines
There are a few guidelines to follow when determining the right hermit crab tank size:
- Allow 2-3 gallons per crab. For 3 crabs, this means a minimum of 6-9 gallons.
- Aim for a 10 gallon tank as the smallest recommended size for 3 hermit crabs.
- Bigger is always better. The more space you can provide, the happier your hermit crabs will be.
- Make sure the tank is wide enough for crabs to comfortably walk and climb. Aim for a width of at least 16 inches.
- Provide 6-10 inches of substrate depth for burrowing and molting.
While a 10 gallon tank meets the minimum requirements, a 20 gallon or larger tank is ideal for 3 hermit crabs. The extra space allows them to spread out, exercise, and get away from each other when needed.
Factors to Consider
When selecting an appropriately sized tank, here are some factors to consider:
Number of Crabs
The number of crabs you plan to house is the primary determining factor for tank size. Allow 2-3 gallons of space per crab as a general rule. The more crabs, the larger tank required.
Size of Crabs
The size of your hermit crabs also matters. Larger crabs will need more space than smaller crabs. Aim for at least 6 inches width per crab.
Tank Shape
Prioritize floor space over height. Hermit crabs need room to walk and climb horizontally, not vertically. A wide, shallow tank is better than a narrow, tall one.
Substrate Depth
Allow for 6-10 inches of substrate at the minimum for digging, molting, and burrowing. Deeper substrate increases the functional space for crabs but doesn’t replace the need for an adequately wide tank.
Decor and Accessories
Make sure to account for tank decor and accessories when figuring space. Things like plants, rocks, driftwood and hides take up room that crabs could otherwise use.
Molting
During molting, hermit crabs are extremely vulnerable. They need extra space to bury themselves safely while shedding their exoskeleton. More space reduces competition for underground molting spots.
10 Gallon Standard Tank Dimensions
A 10 gallon tank is 20 inches long x 10 inches wide x 12 inches high. Here are the key dimensions:
- Length – 20 inches
- Width – 10 inches
- Height – 12 inches
- Footprint – 200 square inches (length x width)
The 10 gallon gives each of 3 hermit crabs about 6-7 inches of width, meeting the minimum requirement. But bigger is still recommended if possible.
20 Gallon Long Tank Dimensions
A 20 gallon long aquarium is 30 inches long x 12 inches wide x 12 inches high. Here are the dimensions:
- Length – 30 inches
- Width – 12 inches
- Height – 12 inches
- Footprint – 360 square inches (length x width)
The 20 gallon long provides about 10 inches of width per crab, giving them more room to spread out and explore.
Other Suitable Tank Sizes
While 10 and 20 gallon tanks are most common, here are some other suitable sizes for 3 hermit crabs:
| Tank Size | Dimensions | Footprint |
|---|---|---|
| 15 gallon | 24 x 12 x 16 inches | 288 square inches |
| 18 gallon | 24 x 12 x 16 inches | 288 square inches |
| 20 gallon high | 24 x 12 x 16 inches | 288 square inches |
| 29 gallon | 30 x 12 x 18 inches | 360 square inches |
| 40 gallon breeder | 36 x 18 x 16 inches | 648 square inches |
The 18-20 gallon sizes give each crab about 9-10 inches of width. The 29 gallon provides 12 inches per crab. The 40 gallon breeder gives each crab a spacious 18 inches!
Creating More Vertical Space
If you have a tank that’s wide enough but lacks height, there are a few DIY options to create more usable vertical space for hermit crabs:
- Add stacked or shelved “levels” using plastic canvas or egg crate light diffuser.
- Attach climbing ramps, ladders, or sturdy branches at an angle.
- Install cork bark wall panels for climbing and hiding.
- Lean natural driftwood at an angle or cross-hatch multiple pieces.
This allows crabs to better utilize the full height of the tank by creating more surface area for climbing and perching.
Maximizing Use of Floor Space
To make the most of the tank’s floor space:
- Choose wide, low profile decor like large shells vs. tall ornaments.
- Use silk or live plants along the back and sides instead of fencing in the middle.
- Arrange decor along the perimeter instead of scattered throughout.
- Allow for several inches of open sand surrounding water and food dishes.
This provides wide open areas for crabs to walk around freely and fully utilize the tank’s footprint.
Tips for Measuring Tank Space
Use these tips for accurately measuring and optimizing the space in your hermit crab tank:
- Measure dimensions from the inside edges, not including trim or frame.
- Calculate footprint by multiplying interior length x width.
- Estimate horizontal surface areas of decor and subtract from footprint.
- Account for substrate depth when figuring vertical space.
- Measure diagonally across tank to find the maximum dimensions.
Taking exact measurements and making some calculations helps ensure your hermit crabs have adequate room to thrive.
Setting Up the Right Habitat
In addition to tank size, a few other habitat factors are key for hermit crabs:
Substrate
Use a coarse, grainy substrate 6-10 inches deep. Play sand mixed with coconut fiber is a popular choice.
Landscaping
Include hiding spots, climbing areas, open floors, and anchor points for molting. Use rocks, wood, bark, and plants.
Heat and Humidity
Maintain a temperature of 70-80°F and humidity around 75-85%. Use an under tank heater and hygrometer.
Water
Provide both fresh and saltwater pools deep enough for crabs to fully submerge. Change frequently.
Food
Offer variety including protein, veggies, calcium and leaf litter. Scatter in multiple dish locations.
Conclusion
For 3 pet hermit crabs, a minimum tank size of 10 gallons is recommended. This allows for the necessary 2-3 gallons of space per crab. However, a larger tank of 20 gallons or more is ideal to give them plenty of room to thrive.
Be sure to also factor in the number and size of crabs, tank dimensions, decor and accessories, as well as substrate depth. Maximizing floor space and adding vertical climbing opportunities can further enhance their habitat.
With an appropriately sized tank filled with 6 inches of substrate, pools of water, ample hiding and climbing areas, and proper heat and humidity, 3 hermit crabs will have the comfortable, enriching home they deserve.
