Yellow Sea Cucumber

Care at a glance

Overview

A small, peaceful filter feeder that is reef safe, since it does not eat coral or bother tankmates, though like every cucumber in this family it carries the same holothurin toxin risk if it is crushed, sucked into a pump, or dies of neglect. It needs one or two feedings a day of phytoplankton or other fine particulate food released into the current well upstream of it, since dosing it directly just makes it clamp shut. Screen every intake in the tank and avoid housing it with triggerfish, puffers, or other bold fish that might peck at it. Because it depends entirely on supplemental feeding and stable water quality, it suits an experienced keeper with an established tank better than it suits a first invertebrate purchase. Drip acclimate it over an hour or more, since like other cucumbers it does not tolerate a fast change in salinity.

In the wild

Yellow sea cucumbers come from the western Pacific around Indonesia and the Philippines, where they anchor to rock and rubble in areas with steady water movement and extend their tentacles to catch passing food. In the aquarium it settles onto live rock in low to moderate flow and tends to stay put once it finds a spot it likes, occasionally relocating a short distance. It needs an established reef system with real planktonic life in the water column, not a newly cycled tank.

Good to know

Colochirus robustus is a small filter-feeding sea cucumber in the family Cucumariidae, the same family as the sea apple, with a stout yellow to orange body covered in short conical papillae and a crown of ten branched tentacles for catching food. It stays considerably smaller than a sea apple, reaching only about 10 cm. It feeds by sweeping suspended particles out of the water with its sticky tentacles and wiping each one across its mouth in sequence, the same feeding method used across the filter-feeding cucumbers.

Did you know

Despite being a close relative of the much showier sea apple, the yellow sea cucumber rarely gets picked at by fish, likely because its duller color and smaller size draw far less attention, which in practice makes it the calmer, lower-drama cousin to keep.

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