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Freshwater Crab

Freshwater Crab

includes red claw crab, fiddler crab and Thai devil crab species

Small and fascinating scavengers, freshwater crabs are also escape artists capable of finding almost any hole in the hood of an aquarium.

Freshwater Crab

Freshwater Crab Facts

average adult size: 1-4 inches across, depending on species
average life span: depends on species
diet: omnivore
minimum aquarium size: 5+ gallons, depending on species
water temperature: 72-82°F


A well-balanced Freshwater Crab diet consists of:

  • Flakes, freeze-dried, pellets or frozen food.
  • Feed a variety of food to ensure complete nutrition.


Things to remember when feeding your Freshwater Crab:

  • Make sure a small amount of food reaches the bottom of the tank; if unsure, drop sinking pellets into the tank at night; alternate protein- and algae-based pellets.
  • Thaw frozen food before feeding.


  • Keep in an appropriate size aquarium; a natural behavior of most crabs is to climb out of the water for brief periods of time, their habitat should Provide them the ability to climb out of the water.
  • Provide plenty of commercial decor, such as rocks, plants and other hiding places.
  • Copper-based medications are toxic to crabs.
  • Stable water quality and parameters are critical to the health of aquatic life. If you are unsure of your water quality, Petco provides free water testing.


  • Active, nocturnal (active at night) scavengers; may eat snails.
  • Crabs can climb almost any surface, including airline tubing and intake tubes; secure holes in aquarium hood to keep crabs inside.
  • All crabs molt; a crab lying on its back may be molting.
  • Crabs benefit from freshwater salt; follow package instructions.

Habitat Maintenance

Daily: check filter, water temperature and other equipment.
Weekly: check water quality at least once a week.
Monthly: change 10-25% of the total volume of water every 2-4 weeks, or as needed.
Introduce new inhabitants to the aquarium gradually.


No more than one crab per square foot is recommended. Do not keep with fish that will harass or eat them, such as certain cichlids. May catch and eat small fish, dwarf African frogs and other tank mates that live or sleep on the bottom of the tank.


Signs of a Healthy Crab

  • Active scavenging
  • Healthy appearance
  • Bright, even coloring

Avoid overcrowded conditions; they are a major cause of stress and disease. Maintain good water quality with regular water changes and adequate filtration.

Common Health Issues

Health Issue Symptoms or Causes Suggested Action
Health IssueLoss of appendage Symptoms or CausesFighting between crabs or due to an aggresive fish. Suggested ActionWill usually regenerate. An iodine supplement can help with the molting process.
Little is known about diseases that affect invertebrates; as long as environmental conditions and food supplies are adequate, invertebrates are fairly resistant to disease.


Ask a store partner about Petco's selection of books on freshwater crabs and the variety of private brand products available for the care and happiness of your new pet. All private brand products carry a 100% money-back guarantee.

Because all aquatic life are potential carriers of infectious diseases, such as Atypical Mycobacterium and Salmonella, always wash your hands before and after handling your aquatic life or habitat contents to help prevent the potential spread of disease.

Pregnant women, children under the age of 5 and people with weakened immune systems should contact their physician before purchasing or caring for aquatic life and should consider not having aquatic life as a pet.

Go for more information about aquatic life and disease.

This care sheet can cover the needs of other species.

Note:The information on this Care Sheet is not a substitute for veterinary care. If you need additional information, please refer to the sources on the following page or contact your veterinarian as appropriate.

Developed with and approved by a qualified veterinarian.