The Crabby is one of the larger Cubaris available in the UK, and one of the few premium species whose appeal survives being photographed badly. It is broad, deep orange, flared with pale yellow down each side, and substantial enough that you spot it the moment you lift a piece of cork. It is also scarce, expensive and sold under two different names, which is why people struggle to find it.
Quick answer
Crabby Isopods are an undescribed Cubaris, also sold as Giant Nguyen, which the trade places in caves in southern Vietnam on a collector's account. Keepers put adults at around 20 to 22 mm, large for a Cubaris. They want 22 to 27°C, high and steady humidity of 70 to 80%, deep calcium-rich substrate and air that moves through the tub. They breed slowly, they are a poor first Cubaris, and a starter group sits at the premium end of the UK market.
One animal, two names
You will meet this species as the Crabby and as the Giant Nguyen, and both refer to the same undescribed Cubaris. European keeper circles tend to use Giant Nguyen; UK retail more often uses Crabby, a nod to the broad, flared, faintly crab-like outline. Listings shorten these variously to Crabby Isopod, Cubaris sp. 'Crabby' and Cubaris sp. 'Giant Nguyen'.
This matters practically rather than academically. Availability is thin, stock surfaces under whichever label the seller prefers, and if you search only one name you will miss half the listings in the country.
Appearance and size
The colour reads first: a rich orange-red across the back, edged with pale yellow flaring down each side. Against dark substrate and brown leaf litter that contrast is what makes the species a display animal rather than a collector's curiosity.
The build is the other half of it. Where most Cubaris are neat and compact, the Crabby is broad-shouldered and visibly heavy, and mature animals have real physical presence in an enclosure. Disturbed, one shuts into a solid orange marble the way all Cubaris do, then unrolls in its own time once it decides the coast is clear.
Where the trade places it, and why that governs the care
The trade places it in the limestone country of southern Vietnam, and although we have found nothing published about the animal, the husbandry that follows is what keepers find works.
We have found no published physiology for Cubaris. No thermal preferendum, no measured water-loss rate, nothing. The literature on terrestrial isopods rests on roughly six temperate and Mediterranean species, so every number quoted for a premium Cubaris in this hobby, ours included, is an extrapolation. We would rather say that plainly than publish confident figures we cannot support.
What we can lean on is one limestone cave that has actually been measured. McClure, Lim and Winn (1967, Pacific Insects 9(3)) recorded terrestrial isopods in Dark Cave at Batu Caves, Malaysia: the cave interior averaged 24.5°C with a monthly range of 23.0 to 25.0°C, while the surface outside reached daily maxima of 28.8 to 30.3°C.
The useful part is that that cave was not hot, it was stable - its whole annual swing was around two degrees, smaller than the surface managed in a single day. Separately, keepers find the Crabby does better kept evenly damp, which is why we do not insist on a drier end in its enclosure. We do the same for the still-air Cubaris such as the Panda King; for most of the rest of our range we build a moisture gradient, a damp end and a drier one, so the animals can choose.
Care
Temperature
Hold 22 to 27°C, and prioritise steadiness over the exact figure. Swings are what cost people colonies with this species. A British home sits below that band through the colder months, so plan on a heat mat or cable on a thermostat, on the side of the tub and never underneath, through the colder months at least, and no heat at all through a warm summer - see our guide on how hot is too hot, because a British July can now push a closed room past the top of that band without any help from you.
Humidity and airflow
High and steady, around 70 to 80%, balanced against real airflow rather than sealed in. Damp like a wrung-out sponge, never wet. If you are unsure, run slightly drier and open up the ventilation: stagnant, humid air kills Cubaris that need airflow, which we know from keeping them rather than from a study.
Cross-ventilation through mesh set into two opposing walls works better than a single vent, because it moves air through the box rather than letting it sit.
Substrate
Give them depth to burrow, around 15 cm. The base wants to be nutritious as well as moisture-retentive: flake soil, white-rotted hardwood and organic topsoil, with crushed limestone worked all the way through rather than sprinkled on top. A large, heavily calcified isopod needs calcium constantly available, not offered occasionally.
Coco coir is the usual shortcut and we would leave it on the shelf. It holds water beautifully and feeds nothing.
Pack the surface with hardwood leaf litter, cork flats and tubes, and a few limestone chunks for cover.
Skip the water dish
Misting and a permanently damp corner cover everything they need. Standing water invites drownings, particularly of mancae, and adds nothing a damp substrate does not already do.
Should you buy one?
Suitable for: keepers with a season or two of Cubaris experience, collectors who want size and colour in one animal, and anyone with a stable warm room and the patience for slow breeding.
Not suitable for: a first isopod, or a first Cubaris. At this price the cost of learning on them is high, and the things that go wrong - swings in temperature, a sealed humid box, thin substrate - go wrong slowly and are hard to reverse once a small colony has stalled. Start with something forgiving and work up. Our Dairy Cow guide is a better first stop, and the Cubaris care guide covers the group in depth.
Buying one in the UK
Availability is the real constraint. This is a recent arrival, colonies are slow to build, and stock appears and vanishes. A few practical points:
- Search both names. Crabby and Giant Nguyen will surface different listings.
- Expect a premium price for a starter group in the UK. Substantially cheaper usually means either a very small count or a misidentified animal.
- Buy captive-bred. Ours are UK-bred, which matters more for a species this scarce than for a common one.
- Check the count and the guarantee. We add 20% over the number you pay for and guarantee live arrival.
- Order early in the week. We post Monday to Thursday so nothing sits in a depot over a weekend, and in hot or freezing weather we hold shipments rather than risk them.
Browse Crabby Isopods, or see the full Cubaris collection.
Frequently asked questions
Are Crabby and Giant Nguyen the same isopod? Yes. Two trade names for the same undescribed Cubaris, sold as coming from southern Vietnam. Neither is more correct than the other, because we have found no formal description of the species.
How big do they get? Keepers put adults at around 20 to 22 mm, large for a Cubaris, and they are noticeably broader than typical species in the group. We have not measured a decent sample ourselves, the species is undescribed so we know of no published figure, and individual size varies with conditions and age.
Do they need a heat mat? Yes, through the colder months at least, on a thermostat. Through a warm summer, no. The band you are aiming for is 22 to 27°C and a modern sealed room can exceed that unaided.
Why are they so expensive? Scarcity and slow breeding. They arrived in the UK recently, colonies build slowly, and demand for large colourful Cubaris is high. Price tracks availability rather than difficulty.
Can I keep them with other isopods? We would not. One species per enclosure is the safer rule generally, and at this price the risk of a faster-breeding species outcompeting them is not worth taking.
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