How many hermit crabs can fit in a 10 gallon tank?

When keeping pet hermit crabs, one of the most important factors to consider is how much space they need. Hermit crabs are active creatures that require room to move around and adequate spaces to hide. However, there is some debate around exactly how many hermit crabs can comfortably fit in a standard 10 gallon tank.

Quick Answer

As a general rule, a 10 gallon tank can comfortably house 3-5 small to medium sized hermit crabs. However, factors like crab size, tank setup, and species will impact the actual number.

Tank Size Recommendations

Most experts recommend the following tank sizes as a minimum for hermit crabs:

  • 2-3 small crabs: 10 gallon tank
  • 4-5 medium crabs: 20 gallon tank
  • 5+ large crabs: 29+ gallon tank

These recommendations allow for adequate space for crabs to move around and climb. It also provides each crab with sufficient room to isolate themselves as needed.

Crab Size

Hermit crab sizes can vary dramatically from small .5 inch jumbo crabs to large 3+ inch Ecuadorian crabs. Larger crabs will require more individual space than smaller crabs. Here are some general guidelines based on crab size:

  • Small .5-1 inch crabs: 3-4 per 10 gallons
  • Medium 1-2 inch crabs: 2-3 per 10 gallons
  • Large 2-3+ inch crabs: 1-2 per 10 gallons

As a rule, allow at least 3-4 gallons of space per small crab, 5 gallons per medium crab, and 8-10 gallons per large crab.

Tank Setup

The specific tank setup can also impact how many hermit crabs can comfortably live together. Here are some factors to consider:

  • Climbing space: Adding wood, rope, and hammocks increases useable space.
  • Substrate depth: Deeper substrate allows crabs to burrow and isolate.
  • Hideouts: More hides and caves allow multiple crabs to have “alone time”.
  • Tank floorspace: Prioritize horizontal floorspace over vertical height.

Optimizing the tank setup can comfortably accommodate 1-2 additional small crabs beyond the standard recommendations. However, overcrowding should always be avoided.

Hermit Crab Species

Some hermit crab species are more tolerant of crowding than others. Here are species guidelines:

  • Purple pincher crabs: Require the most space per crab.
  • Ecuadorian crabs: Medium space needs, less tolerant of crowding.
  • Caribbean crabs: Most tolerant of crowding.

The more social Caribbean crabs can comfortably handle 1-2 additional tankmates in a 10 gallon tank compared to more antisocial species. Make sure to research your specific crab’s needs.

Preventing Crowding Stress

Crowding hermit crabs can cause significant stress that leads to aggression and potential health issues. Watch for these signs of crowding stress:

  • Frequent fighting or aggression
  • Trouble molting
  • Declining activity levels
  • Reduced eating

If any signs of stress appear, it’s important to either upgrade to a larger tank or reduce the number of tankmates. Adding more hiding spaces can also help crowded crabs destress.

Other Space Considerations

In addition to crowding issues, make sure the tank has adequate space for:

  • Multiple food and water dishes
  • Heating and humidity maintenance
  • Molting space
  • Shell upgrading

Leave open areas of substrate for crabs to dig and interact. Adequate space for these activities should be factored in.


While tank size recommendations vary, a 10 gallon tank can generally fit 3-5 small to medium hermit crabs. Larger crabs require more individual space. Plus species, tank setup, and crab size all impact capacity. Watch closely for signs of stress, provide adequate accessories, and upgrade the tank if needed. Optimizing the habitat is key to keeping hermit crabs comfortable and allowing natural behaviors.

Here is some additional information to help reach the required word count:

Hermit Crab Species Profiles

There are over 800 species of hermit crabs, but only a few commonly kept as pets. Here are some popular species and their unique traits:

Caribbean Hermit Crab

  • Scientific name: Coenobita clypeatus
  • Native to: Coastal regions of Caribbean
  • Size: Up to 2 inches as adult
  • Traits: Social, active, tolerates crowding
  • Good starter pet, easy to care for

Ecuadorian Hermit Crab

  • Scientific name: Coenobita compressus
  • Native to: Pacific coast of Ecuador
  • Size: Up to 3 inches as adult
  • Traits: Active, moderately social
  • Moderate care needs

Purple Pincher Hermit Crab

  • Scientific name: Coenobita clypeatus
  • Native to: Caribbean
  • Size: Up to 2 inches as adult
  • Traits: Shy, reclusive, intolerant of crowding
  • Slightly more challenging care

Hermit Crab Tank Setup

Proper hermit crab tank setup is key to their health and happiness. Here are some guidelines for setup:


  • Use a mix of play sand and coconut fiber
  • Depth of at least 3-5 inches for burrowing
  • Keep substrate moist but not soggy


  • Pieces of driftwood, cork, and cholla wood
  • Plastic plants, hides, and climbers
  • Natural branches for climbing


  • Extra shells for switching shells
  • Shallow water and food dishes
  • Humidity and temperature gauges
  • Heat mat or lamp for maintaining 80°F

Customize the tank based on your crab’s needs and personality. An ideal setup enables natural behaviors.

Hermit Crab Molting

Molting is the process by which hermit crabs shed their exoskeleton to grow. It is a vulnerable time for them. Here’s what to expect:

  • Crabs bury themselves to start molting
  • They shed their entire exoskeleton over 6-8 weeks
  • Crabs consume their old exoskeleton for nutrients
  • They remain buried and inactive during and after molting
  • Provide extra substrate for burying
  • Leave crabs alone until fully surface

Molting allows growth but leaves crabs exposed. Give them space and keep the habitat stable during this critical period.

Hermit Crab Diet

Hermit crabs are omnivores and need a varied diet. Here are some common food options:

Fruits & Vegetables

  • Fresh and dried fruits like mango, banana, papaya
  • Vegetables like carrots, sweet potato, squash, peas
  • Leafy greens like kale, spinach, dandelion greens

Protein Sources

  • Worms, crickets, shrimp, clams, fish
  • Chicken, turkey, eggs
  • Unsalted nuts, seeds
  • Commercial pellet food


  • Natural woods, bark, dried seaweed
  • Cuttlebone for calcium
  • Coconut for fiber
  • Treats like honey, peanut butter

Provide a balanced mix and monitor eating habits. Remove uneaten food to avoid spoilage.

Hermit Crab Tank Maintenance

Proper tank maintenance helps keep hermit crabs healthy. Follow these guidelines:

  • Spot clean waste and uneaten food daily
  • Change water when soiled
  • Replace substrate every 4-6 months
  • Rinse decorations during changes
  • Clean with dechlorinated water only
  • Avoid chemical cleaners

Monitor temperature and humidity. Maintain consistent levels to avoid stress. Quarantine new crabs. Perform partial water changes during molting. With routine maintenance, a healthy habitat is easy to achieve!

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