Stichopus chloronotus

Acclimation: sea cucumbers are sensitive to changes in salinity. Acclimate it slowly by drip in a separate container, then move it without pouring the shipping water into the tank. Handle it as little as possible and with gloves: handling or relocating it can by itself trigger the release of holothurin. Handling: its body wall readily disintegrates outside seawater. Always move it in a submerged container, never lifting it out of the water.

Setup: it needs a tank with plenty of sand. Meerwasser-Lexikon rates it unsuitable for aquarium keeping, and LiveAquaria sells it as expert only. Do not overstock: the usual rule of thumb is about 7.5 cm (3 inches) of sea cucumber per 75 litres (20 gallons), and an average reef tank can only feed one or two.

Fit every pump, powerhead and overflow intake with a large, securely fixed strainer: according to Rob Toonen, most 'cuke nukes' happen when a sea cucumber is sucked in and shredded. If it happens anyway, remove the animal at once, make a large water change, increase skimming and add activated carbon.

Sensitivities: like other sea cucumbers, it can release toxins when stressed or injured, which may kill fish. Like other invertebrates, it tolerates neither copper treatments nor high nitrate; never put it in a copper-treated tank, not even in quarantine. For you: sea cucumber toxins (saponins such as holothurin) irritate skin and mucous membranes; eye contact can cause serious injury, including blindness in reported cases. Wear gloves when you work in the tank.

Water: aim for 22 to 25.5 °C, a specific gravity of 1.020 to 1.025, pH 8.1 to 8.4 and 8 to 12 dKH.