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Marine Crustacean

Marine Crustacean

includes shrimp, lobsters, hermit crabs, emerald crabs, decorator crabs and sally lightfoot crabs

Marine crustaceans are best known for their joined outer shell. Many shed or molt their hard exoskeleton as they grow. Crustaceans, such as crabs, shrimp and lobster, can be vivid in color and fast-moving.

Marine Crustacean

Marine Crustacean Facts

Average Adult Size 2 to 12+ inches long, depending on species
Average Life Span depends on species
Diet omnivore and herbivore, depending on species
Minimum Aquarium Size 29 to 50 gallons, depending on species
Water Temperature: 72-78°F
Salinity Level: 1.023-1.025


A well-balanced marine crustacean diet consists of:

  • Frozen brine or mysis shrimp.
  • Usually feeds off excessive food or debris in the tank.
  • Certain species are herbivores and eat algae.


Things to remember when feeding your marine crustacean:

  • Feed 2 to 3 times a day.
  • Thaw frozen food before feeding.


  • Keep in an appropriately sized aquarium; provide hiding places or caves, appropriate depth of substrate based on species and plenty of décor for marine crustaceans to protect themselves.
  • Use of copper-based medications is toxic to crustaceans.
  • The use of an iodine supplement can be beneficial during a crustacean's molting process.
  • 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.

Normal Behavior

  • Small crabs and shrimp make excellent first crustaceans.
  • Some crustaceans are known to eat small fish and invertebrates.
  • May become aggressive toward some species in smaller aquariums.
  • Many species provide great natural algae and parasite control.

Habitat Maintenance

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


  • Marine crustaceans are usually not compatible with mollusks, squid and octopuses. Caution should be used when adding crustaceans to a tank that contains slow-moving aquatic life or aquatic life known to eat crustaceans.


Signs of a Healthy Crustacean

  • Healthy appetite
  • Even coloring
  • Sleek, non-pitted shell and legs (applicable to certain species)

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

Red Flags

  • loss of color or appetite
  • spots or fungus on body
  • erratic movements
  • disfigurement
  • Missing limbs or antennae

Common Health Issues

Health Issue Symptoms or Causes Suggested Action
Health Issue Body or surface erosion Symptoms or Causes Poor water quality; nutrient deficiency. Suggested Action Test and treat water immediately; maintain proper diet.
Health Issue Loss of appendage or antennae Symptoms or Causes Fighting between crustaceans or due to an aggressive fish. Suggested Action Will usually regenerate. An iodine supplement can help with the molting process.


Ask a store partner about Petco's selection of books on marine crustaceans 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, senior citizens 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 to the Centers for Disease Control at 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.