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Black Sea Cucumber

(Holothuria atra)

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 Quick Care Facts

• Care Level: Expert   • Temperament: Peaceful   • Maximum Size: 24"
• Diet: Omnivore   • Aquarium Level: Bottom   • Minimum Tank Size: 125 gallons
 • Reef Compatible: Yes   • Water Conditions: 72-78° F, dKH 8-12, pH 8.1-8.4, sg 1.023-1.025
• Supplements: None   • Coloration: Black
• Origin: Indo-Pacific • Family: Holothuriidae   • Species: Cucumbers

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Native Habitat and Species Information

Black Sea Cucumber native habitat, distribution, behavior & aquarium compatibility.

The Black Sea Cucumber, or as it is often referred to as the Black Cucumber, Black Sea Urchin, or Lollyfish, has a long black body with a few spots. This species is usually found living in sandy bottom areas where it will often partially cover itself with sand. This is a very peaceful species, but can be dangerous if it is stressed or killed, as it can release dangerous toxins into the water. In the aquarium environment these toxins can be fatal to other species in the aquarium including fish.

Aquarium Care

How to successfully keep Black Sea Cucumber in the home aquarium.

The Black Sea Cucumber needs to be kept with peaceful tank mates, that will pick at it or cause it undue stress. Do not overstock an aquarium with the Black Sea Cucumber, in general, keep only 3 inches of worm for every 20 gallons of water. The Black Sea Cucumber is very sensitive to high levels of copper-based medications and will not tolerate high nitrate levels.

Being a sand sifting organism, it is important that the Black Sea Cucumber be kept in an aquarium with a sand bottom, so that it will be able to burrow and feed.

Feeding & Nutrition

How to feed and provide proper nutrition for Black Sea Cucumber.

The Black Sea Cucumber is a sand sifter and will ingest large amounts of sand eating any small food particles present in the sand and then expelling the clean sand. The Black Sea Cucumber is an excellent sand sifter and keeps the aquarium substrate clean and free of dead spots where excess food can break down in the substrate fouling the water.


Caution! Black Sea Cucumber can release toxins.

Caution! Black Sea Cucumbers have the ability to releases toxins (venom) that may kill fish in the aquarium when they are severely stressed or damaged by pump intakes or overflows. It does not have tubules of Culvier, but in the wild, if it is attacked or injured, it will expel its internal organs, which can be toxic to fish. After the Black Sea Cucumber escapes, it will regenerate those organs, although this regeneration rarely occurs in an aquarium setting.

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