Cubaris sp. 'Black Sapphire' Isopods

Most Cubaris arrive dressed in pale creams, warm oranges or busy patterns, which is exactly why the 'Black Sapphire' stops me every time I lift its lid. This is a Cubaris sp. in deep, lustrous solid black, a dark gemstone of an isopod with no stripes, no speckle and no fade, just a clean obsidian sheen that catches the light as it moves. Set against pale substrate it looks less like a woodlouse and more like a polished stone that decided to walk.

The 'Black Sapphire' comes from the same Thai stock as the famous Rubber Ducky, and you can see the family resemblance in the rounded body and that soft "ducky" facial profile. Adults reach around 18 mm, they live two to three years in good conditions, and like every Cubaris they conglobate, rolling into a tight ball when startled. It is the Rubber Ducky silhouette I know so well, only rendered in black rather than gold.

These are warmth-loving animals, happiest somewhere around 22 to 26°C, so a heated room in a UK home usually suits them without extra kit. They want high humidity with a gradient rather than a soaking wet box: keep one end damp with sphagnum and mist there, leave the far end drier, and run good cross-ventilation between the two. Damp like a wrung-out sponge is the target, never waterlogged. If I am ever unsure, I err a touch drier and open the airflow, because overwetting is the fastest way to lose a colony on this tier.

Substrate does a lot of the work. I build a living base of flake soil, rotted hardwood and topsoil rather than a plain coco-coir mix, which gives the springtails and microfauna something to feed on and holds a steady moisture gradient. Through it I fold plenty of calcium in the form of crushed limestone or oyster shell, which these cave-origin Cubaris draw on for their moults. On top I pile a deep layer of magnolia leaf litter with cork bark for cover, and I always seed the tub with a springtail culture to keep mould in check in that humid air.

A word on what you will actually see. Like most Cubaris, the 'Black Sapphire' is shy and largely nocturnal, so it spends much of the day tucked under bark and leaf litter. This is a colony you lift a hide to admire rather than one that parades across the glass, and the black really sings against a pale background while it can vanish against dark substrate, so I would light and landscape the tub with contrast in mind.

I will be straight with you: the 'Black Sapphire' is a premium species from the more demanding end of the Rubber Ducky line, and it breeds slowly. Colonies build at a patient, steady pace over months rather than exploding, so this is not the isopod to cut your teeth on. If you are newer to the genus, start with hardy Cubaris murina and come back once you can hold stable conditions. For collectors, it sits beautifully beside the established Black Pearl and the tricolour Rubber Bee.

Every order is captive-bred here, never wild-caught, and it goes out boxed double-walled around a ventilated tub of damp sphagnum. I post Monday to Thursday by tracked next-day Royal Mail, with a live-arrival guarantee and a 20% overcount added as standard. If anything looks amiss when your parcel lands, message me the same day and we will put it right.