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The Emerald Crab, scientifically known as Mithraculus sculptus, is a fascinating and beneficial invertebrate that can contribute to the overall health of a marine aquarium. Known for its striking green coloration and algae-eating habits, the Emerald Crab is a popular choice among reef enthusiasts.



  • Average Size: 1-2 inches
  • Max Size: 2 inches
  • Tank Size Required: 20 gallons or larger


Temperament: The Emerald Crab is generally peaceful and is compatible with most reef inhabitants. It is an efficient algae eater and contributes to algae control in the aquarium. However, it may exhibit territorial behavior towards other crabs.


Unique Traits: As the name suggests, the Emerald Crab is characterized by its vibrant green coloration, making it stand out in a marine aquarium. Its distinctive appearance, coupled with its algae-consuming habits, makes it a valuable addition for maintaining a clean and balanced tank.


Origin: Native to the Caribbean and the Gulf of Mexico, the Emerald Crab is typically found in rocky or coral-rich areas, where it can actively forage for algae and detritus.


Other Names:

  • Emerald Crab
  • Green Mithrax Crab


Care Level: Easy


Diet: The primary diet of the Emerald Crab consists of algae and detritus. It is known for its efficiency in controlling hair algae and other undesirable algae types in the aquarium. Additionally, supplement its diet with algae sheets and other marine invertebrate food.


Characteristics and Looks: The Emerald Crab exhibits a bright green coloration, and its body has a distinct, flattened shape. Its claws are adapted for feeding and may have small hairs for filter-feeding. The overall appearance adds a pop of color and interest to the aquarium.


Water Parameters:

  • pH: 8.1-8.4
  • gH (General Hardness): 8-12 dGH
  • kH (Carbonate Hardness): 8-12 dKH
  • TDS (Total Dissolved Solids): 32-45 ppm
  • Temperature: 72-78°F


Disclaimer: "Please note that these are general guidelines, and for more accurate values, we encourage you to contact Living Aquarium by phone or in person. Within store hours, our team of experts is always happy to answer any questions you may have and provide personalized guidance on care."

Emerald Crab

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