Cleaning is among the major aspects of any crab tank. Sometimes, it felt hard. However, if you follow a certain cleaning routine, it’s easy. Other than cleaning, humidity is a key factor in a clean crab tank. In the following, you’ll learn how to keep humidity in a crab tank appropriately, and a crab tank maintenance schedule.
Content Table
Crab Tank Peculiarities
Crab tanks are different from regular fish or planted tanks in many ways. Here are some peculiarities of a crab tank.
Peculiarities
- The minimum tank size should be 5 gallons. It can go up to 75 gallons.
- They have semiaquatic habitats, i.e., both land and water.
- Usually, crab tanks have sponge filters.
- Crab tanks have moist sand or fine gravel, as crabs love to dig into it.
- It has numerous hiding spots, e.g., caves, driftwood, PVC pipes, or artificial plants.
- They have high humidity levels, i.e., 75% to 85%, and75-85°F temperature.
- These tanks have a tight lid at the top to prevent crab’s escape.
Differences Between a Crab Tank and Fish Tanks/Planted Tank
Features | Crab Tank | Fish Tank | Planted Tank |
Water type | Fresh and brackish water | Fresh and brackish water | Freshwater |
Land and water area | Semiaquatic | Fully aquatic | Fully aquatic |
Filtration | Sponge filter | HOB, canister, sponge, or sump filter | Canister, sponge, or plant-specialized filters |
Tank bottom | Sand, fine gravel, and moist soil | Gravel, sand, or bare bottom | Nutrient-rich soil, gravel, or sand |
Tank lid | Essential tank lid | Optional | Optional |
Humidity control | Humidity control | Not required | Not required |
Light intensity | Low to moderate | Specie dependent | High |
Decoration and hiding spots | Essential for molting | Specie dependent | Only decoration |
Equipment. | Heat mats and salt for brackish water | Heater, aeration system | CO₂ system, fertilizers, high-light setup |
What Should the Humidity Be in a Crab Tank?
Humidity is an essential feature of any crab tank. Usually, it ranges from 75 to 85%. The question is why it is necessary to set humidity so high in a crab tank. Here is the reason.
The crabs breathe with their gills, which require moisture for proper functioning. In low or dry conditions, they begin to suffocate and become stressed.
Keep Humidity in Crab Tanks
Maintaining the proper humidity level in your crab tank is highly necessary. It’ll help to increase the life expectancy of your pet crabs. Here are three humidity aspects, i.e., how to increase, decrease, and maintain it in your tank.
How to Increase the Humidity?
- Use moist sand, eco-earth, or coconut fiber as a substrate, and keep it thick for 3 to 6 inches.
- Moist your substrate for once or twice a day. However, avoid over-moisturizing as it can cause mold and bacterial growth in your tank.
- Increase the water area. You can do it by increasing the size of the water-holding dish. Moreover, put a sponge in the tank as it retains moisture for a long.
- Always cover the top with a metallic or acrylic lid.
- You can increase it by adding Sphagnum moss in the tank. It has exceptional moisture-holding capacity.
- Use a humidifier or fogger in large tanks.
How to Lower the Humidity?
Humidity should remain within a safe limit. Otherwise, it will cause problems. You will see mold or bacterial infection problems in the tank. Here is how to decrease it or bring it to the safe limit.
- Improve the tank ventilation.
- Reduce the water area size. You can do it with a small water dish instead of a large one.
- Re-program your humidifier. Turn the humidifier on when the humidity level reaches 75%.
- Remove unnecessary moisturizing elements.
- Let the substrate dry a little before adding the water to the water area.
How to Maintain Moisture?
- Install a hygrometer to check the humidity level in the tank.
- Use moisture-retaining substrate, i.e., coco coir, fine sand, etc.
- Keep it away from fans, direct sunlight, and air conditioners.

clean crab tank
How to Clean Crab/Hermit Crab Tanks
Freshwater Crab
Thai Micro Crab, Vampire Crab, and Panther Crab are examples of freshwater crabs. If you have any freshwater crabs, follow the following cleaning routine.
Daily
- Remove the uneaten food.
- Remove the shredded leaves and molted shells.
Weekly
- Remove the algae from the tank valve with some algae scraper or soft sponges.
- Use gravel cleaner or substrate cleaner to clean the tank’s bottom.
Monthly
- If there is any visible stain or other thing, clean the decorations. However, avoid using bleach or detergent for cleaning. They are harmful to the crabs.
- Clean the filter media or filter floss.
Saltwater Crab
Daily
- Remove the leftover or uneaten food from the tank.
- Remove any dead fellow from the tank.
Weekly
- Change 10% water from the saltwater crab tank.
- Clean the algae from the tank.
Monthly
- Clean the protein skimmer.
- Clean the filter media.
- Rinse the decors in the tank, if there is any visible stain.
Brackish water Tank
Brackish water is mildly saline, i.e., to some extent freshwater, mixed with saline water. Fiddler Crab, Red Claw Crab, and Thai Devil Crab are examples of such tank habitats.
Daily
- Do spot cleaning with the help of a cleaning brush.
Weekly
- Clean the land area for semiaquatic crabs.
Monthly
- Rinse and clean the filter media.
- Scrub algae from the wall and decors.

crab tank maintenance schedule
Hermit Crab Tank
Daily Cleaning
- Use a turkey buster to remove uneaten food, i.e., spot cleaning.
- Remove the waste or debris from the tank.
- Take care of other regular cleaning issues.
Weekly or Bi-Weekly
- Clean the climbing structures, e.g., decors, plants, etc.
- Clean the highly damped spots on land areas as they can cause infection.
Deep Cleaning (3–6 months)
When you feel a strong odor or the presence of flies or mites, it is time to clean your crab tank deep. Here are some perspectives on deep cleaning.
- Replace the substrate.
- Wash the tank with vinegar or hot water to disinfect the tank. Don’t use any chemicals for cleaning, as hermit crabs are sensitive to chemicals.
- Boil the empty shells and toys for up to 3 minutes and clean them.
- Remove everything and thoroughly wash it.
Crab Tank Maintenance Schedule
Cleanliness is among the most important maintenance aspects of any crab tank. The remaining maintenance aspects are as follows.
Frequency | Freshwater crab | Saltwater crab | Brackish water crab | Hermit Crab |
Daily | Check equipment and water coloration, i.e., clarity. | Check the equipment, i.e., filters, protein skimmer, etc. | Check the water salinity, i.e., 1.005–1.015 SG. | Refill the water dish with dechlorinated water. |
Weekly | Change 20- 30% water in the tank. | Check the powerhead and pump, i.e., are they functioning properly or any fixable issue is there? | Change consistently 10% water by using a siphon. | Mistify your tank to maintain the humidity between 75 to 85%. |
Check the water parameters, at least once a week. | ||||
Monthly | Deep cleaning | Deep cleaning | Deep cleaning | Deep cleaning |
Concluding Thoughts
The crab tank is unique from many others in several aspects, e.g., semi-aquatic setup, high humidity, tight lid, etc. Keep the humidity between 75 to 85%. Over or under this range cause problems. Follow daily, weekly, and monthly cleaning and maintenance routines to see happy crabs in your enclosure.
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