Description
Candy Cucumber (Colochirus crassus)
(Also known as the Sea Apple Cucumber, Pink and Yellow Sea Cucumber, or Candy Sea Cucumber)
Overview
The Candy Cucumber is a beautifully coloured sea cucumber species admired for its vibrant red, orange, and yellow body, often marked with white or pink bands and small tube feet. Growing to around 10–15 cm (4–6 inches), this species adds unique movement and colour to reef aquariums. Colochirus crassus is a suspension-feeding cucumber, meaning it extends feather-like feeding tentacles into the water to catch plankton and organic matter. Though striking in appearance, it requires a mature, stable aquarium with steady plankton availability and gentle flow to thrive.
Origin
Native to the Indo-Pacific region, including Indonesia, the Philippines, Fiji, and the Great Barrier Reef. Found in lagoons and sheltered reef slopes, often positioned in areas of gentle current where planktonic food is abundant.
Feeding
The Candy Cucumber is a filter-feeding detritivore that relies on suspended micro-foods in the water column. In captivity, it should be target-fed regularly with:
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Phytoplankton (live or concentrated)
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Marine snow or coral plankton blends
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Microparticle coral foods (e.g., Reef-Roids, powdered zooplankton)
Feed 3–4 times per week. Target feeding near the tentacles helps ensure adequate nutrition, as many systems are too clean to sustain them naturally.
Water Flow
Low to moderate, indirect flow. Provide enough current to carry suspended food particles across the feeding tentacles but avoid direct jets that may cause stress or make it retract.
Lighting
Low to moderate lighting. This species does not photosynthesise, so light intensity is unimportant beyond what benefits surrounding corals. Too much direct light may cause the cucumber to hide.
Placement
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Position the cucumber on stable rockwork or sandy substrate in areas of gentle, consistent current.
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It will move slowly across the substrate or rock, using tube feet to anchor while feeding.
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Ensure it cannot be sucked into pump intakes or wavemakers — use foam guards or strainers for protection.
Tank Mates
Compatible with peaceful reef fish and invertebrates. Suitable companions include:
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Clownfish, gobies, blennies, and small wrasses
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Other filter feeders and soft corals
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Snails, hermits, and starfish
Avoid:
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Aggressive or predatory fish (triggers, puffers, large wrasses)
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Overly active tank mates that may disturb its feeding behaviour
Aggression
Peaceful. However, like many sea cucumbers, it can release toxins (holothurin) if severely stressed or injured. While rare in captivity, this can harm fish or invertebrates. Handle with extreme care, ensure good oxygenation, and avoid physical disturbance.
Experience Level
Advanced. Though not difficult if fed properly, Candy Cucumbers require stable, mature aquariums with sufficient suspended nutrition and flow. Starvation is the most common cause of failure.
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) for a single specimen
Maintain excellent water quality and avoid copper-based medications or sudden parameter changes.
Reef Compatibility
Reef safe with caution. Will not harm corals or invertebrates and helps remove dissolved organics, but care is needed to prevent stress or entrapment in powerheads. Ideal for mature reef systems with consistent plankton feeding routines.
