Scarlet Isopods (Ardentiella sp.)

Let me be straight from the outset: the Scarlet is neither an easy isopod nor a cheap one. But for the keeper who is ready for it, few species in the whole hobby are as spectacular - a deep, glowing red splashed with yellow and black that only grows richer with every moult. This is a rare, demanding and genuinely show-stopping animal, and one to take on with your eyes open.

Introduction

The Scarlet is Ardentiella sp. "Scarlet", a selectively-bred colour morph developed from Ardentiella sp. "Tricolor" stock and native to Vietnam. If you have read older listings you may know the genus as Merulanella; it was reclassified to Ardentiella, but both names describe the same group and the care is identical either way. Where its cousin the Ember Bee is one of the more forgiving members of the genus, the Scarlet sits firmly at the demanding end: it was isolated for its intense red pigmentation, and it carries the sensitivity that often comes with the rarest colour lines.

Appearance

Scarlets are large, reaching around 18-20 mm, with a predominantly red body broken by yellow and black splotching. No two are marked quite the same, the segment edges can look faintly translucent, and, rewardingly, the colour deepens as an animal matures, each moult intensifying the red. They are also among the more watchable isopods you can keep: active, curious and often out and about by day, rather than a shy burrower that vanishes into the substrate.

Care

This is where the Scarlet earns its reputation as a difficult species, and where attention to detail counts. Three things matter most:

• Temperature. They are heat-sensitive and do best on the cooler side, around 19-24°C. Let them get too warm and a colony can decline quickly, so keep them clear of heat sources and err cool.
• Humidity and airflow together. They want high humidity but also genuinely good ventilation, which is trickier than it sounds, since most ways of raising humidity also cut airflow. Aim for a well-ventilated enclosure with damp, structurally rich hiding areas rather than a sealed, stuffy box.
• Climbing and escape. Ardentiella are climbers with arboreal leanings, so they will scale anything they can and slip through any gap. A secure, escape-proof enclosure is non-negotiable, and they genuinely appreciate verticality: branches, cork bark and mossy wood to clamber over.

Because they climb and forage on the surface more than they burrow, the substrate matters a little less than it does for a cave Cubaris, but it should still be a nutritious, moisture-holding base of flake soil, white-rotted hardwood and organic topsoil rather than inert coco coir. Keep a calcium source such as cuttlebone or crushed limestone available throughout. Our substrate guide and calcium guide cover the essentials, and the husbandry in our Red Diablo care guide, another Ardentiella, transfers almost directly.

Diet

Scarlets feed as detritivores, working through leaf litter and white rotten wood, which should form the bulk of the diet. Supplement with small amounts of vegetables such as courgette, sweetcorn and sweet potato, and a little protein like fish flake now and then. A springtail culture alongside them helps keep the humid enclosure clean. Our guide to what isopods eat has the full picture.

Breeding

For all their fussiness over environment, Scarlets breed readily once they are settled and their conditions are right; the challenge is getting them to that stable, established point, not the breeding itself. Hold conditions steady and cool, keep food and calcium constant, secure the enclosure and be patient. With a rare and valuable species, a slow, careful start pays for itself.

Who is this for?

The Scarlet is strictly a species for experienced keepers, ideally those who have already succeeded with other tropical isopods, whether a Cubaris like our best-selling Rubber Ducky or a more forgiving Ardentiella like the Ember Bee. It rewards the collector chasing exceptional colour and the keeper who wants isopods they will actually see, out climbing and foraging. It is emphatically not a first isopod, nor one for anyone who cannot hold temperature and humidity steady or secure an escape-prone climber. If that is not you yet, it is well worth building experience on easier species first. Explore the genus in our Ardentiella collection.

Every Scarlet is captive-bred here in the UK and goes out under our live arrival guarantee, travelling in a ventilated deli tub of sphagnum moss within a double-walled box. Dispatch is Monday to Thursday only, keeping your animals out of the post over the weekend.