Description
Caramel Cucumber (Holothuria hilla)
(Also known as the Tiger Tail Cucumber or Sand-Sifting Sea Cucumber)
Overview
The Caramel Cucumber (Holothuria hilla) is an attractive, hardy, and highly beneficial sand-sifting sea cucumber. It features a caramel-brown body often speckled or mottled with cream and white markings, giving it a tiger-like appearance. Growing to around 20–25 cm (8–10 inches) in captivity, it plays a vital role in maintaining a clean, healthy substrate by consuming detritus and organic debris. Peaceful and reef safe, it is an excellent addition to mature reef aquariums with established sand beds.
Origin
Native to the Indo-Pacific region, including Indonesia, the Philippines, Fiji, and northern Australia. Found on sandy lagoon floors and reef slopes where it feeds on detritus-rich sediment.
Feeding
The Caramel Cucumber is a deposit feeder, meaning it ingests sand and filters out organic particles and microorganisms for nutrition. In aquariums, it will naturally feed on detritus and leftover food within the substrate. Supplemental feeding is beneficial in cleaner systems:
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Finely crushed pellets or sinking wafers
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Powdered coral foods or marine snow (targeted on sand bed)
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Light dusting of powdered algae or microfauna foods
Feed 1–2 times weekly if the substrate is very clean or lightly stocked.
Water Flow
Low to moderate flow. Gentle current helps distribute detritus and fine organics through the substrate but avoid strong directional flow that could displace the cucumber or expose it.
Lighting
Low to moderate lighting. As a non-photosynthetic detritivore, the Caramel Cucumber does not depend on light. It prefers shaded or partially lit areas and will remain active during both day and night.
Placement
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Best suited to fine, soft sand substrates at least 5 cm (2 inches) deep.
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Avoid coarse or sharp substrate that could damage its soft body.
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Protect from powerhead and overflow intakes using foam guards or strainers — cucumbers can be drawn in if not shielded.
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May occasionally climb rockwork but primarily stays on or within the sand.
Tank Mates
Peaceful and fully reef safe. Compatible with:
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Clownfish, gobies, blennies, tangs, wrasses (reef-safe species)
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Shrimp, crabs, snails, and other clean-up crew
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Corals of all types
Avoid:
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Predatory fish such as triggers, puffers, and large wrasses that may nip or disturb it.
Aggression
Peaceful. Does not harm tank mates or corals. However, if severely stressed or injured, Holothuria hilla can release a mild toxin (holothurin) — though this is rare in captivity. Maintaining stable conditions and protecting it from pump intakes prevents stress-related incidents.
Experience Level
Intermediate. Very hardy and low-maintenance once established, but requires a mature, established aquarium with sufficient natural detritus and a stable sand bed ecosystem.
Water Parameters
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Temperature: 24–27°C (75–81°F)
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pH: 8.1–8.4
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Salinity: 1.024–1.026 SG
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Hardness (dKH): 8–12
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Nitrate: <10 ppm
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Tank Size: Minimum 75 gallons (280L) with a sand bed of at least 2–3 square feet
Maintain consistent water quality and oxygenation; avoid sudden changes in salinity or temperature.
Reef Compatibility
Reef safe. The Caramel Cucumber is an excellent reef janitor that helps keep sand beds clean and aerated without disturbing corals or invertebrates. It is ideal for natural reef systems where it contributes to nutrient recycling and substrate health.
