A Glimpse
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Scientific Name: Ardentiella sp. "Pastel" (formerly Merulanella sp.)
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Common Name: Pastel Isopod
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Family: Armadillidae
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Origin: Vietnam
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Adult Size: 18–20 mm — a large species by isopod standards
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Difficulty: Hard — captive bred stock is more forgiving, but this is not a beginner species
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Temperature: 19–26°C — prefer the cooler end
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Humidity: 60–75%
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Ventilation: High — essential for this genus
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Diet: Leaf litter, white rotten wood, lichen, moss, vegetables, protein supplements
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Supplements: Cuttlebone, crushed limestone, or oyster shell for calcium
Pastel Isopods: Overview
Ardentiella "Pastel" is one of the most sought-after morphs in the Ardentiella genus, and it's not hard to see why. The colouration is genuinely unlike most other isopods — soft, muted tones in the pastel range rather than the bold, saturated colours you see in morphs like Ember Bee or Lava. The exact palette varies between individuals and even between broods, which is one of the more exciting aspects of keeping a colony. Each new generation can produce slightly different colour expressions, giving you an evolving display rather than a static one.
Like all Ardentiella (formerly classified under Merulanella before the genus was revised), Pastels are Vietnamese isopods that share the same fundamental care requirements across all morphs. If you already keep Batman, Ember Bee, Lava, Tricolor, or any other Ardentiella, the husbandry will be identical. The only things that change between morphs are appearance and price — and Pastel sits at the top end of both.
These are large, active, bold isopods. They're semi-arboreal — they climb, they explore, and they spend time in the open during the day as well as at night. That visibility is a major part of the appeal, especially combined with their colouration. Most isopod species spend the majority of their time hidden. Ardentiella don't.
Why They're Rated Hard
The same two factors that challenge keepers with every Ardentiella morph apply here:
Ventilation vs humidity. Ardentiella need the enclosure to be humid enough for their comfort but airy enough that moisture doesn't become stagnant. The substrate should be able to dry out at the surface without remaining permanently wet throughout. You need cross-ventilation — mesh vents on opposite sides of the enclosure — so that air moves through rather than sitting. Stagnant humid air kills Ardentiella faster than almost anything else. This is the single most important thing to get right.
Frass buildup. Ardentiella are notably sensitive to their own waste accumulating in the substrate. As frass builds up, it raises substrate acidity, and colonies can crash quickly once this passes a threshold. Replace the substrate every 6 months at minimum. If it starts looking dark, compacted, or spent before then, swap it out early.
The CB advantage. Captive bred Ardentiella are dramatically easier than wild caught. The genus has a reputation for being fragile, but that reputation comes largely from WC animals imported in bulk that often arrive stressed and fail to establish. CB populations that have been stabilised over several generations breed readily and are much more forgiving. If you're buying from us, you're getting CB stock, and that makes a real difference to your chances of success.
Enclosure
The enclosure must be escape-proof. Ardentiella — especially mancae and small juveniles — can climb smooth vertical plastic like cockroaches. If there's a gap in the lid, they will find it. Use a tight-fitting lid and check for openings.
These are semi-arboreal isopods that actively use vertical space. Provide a mix of horizontal hides and vertical climbing surfaces: cork bark pieces (both flat and angled), lichen-covered twigs, and small branches. The more three-dimensional the enclosure, the more natural behaviour you'll observe and the more you'll actually see your isopods.
Substrate
Use a mix of forest humus (organic topsoil) with cork granules, crumbled white rotten hardwood, and dried leaf litter. The cork granules help with drainage and prevent the substrate from becoming waterlogged — an important detail for Ardentiella, where the substrate needs to be able to dry at the surface while retaining some moisture deeper down.
Depth should be at least 8–10 cm. Top generously with whole leaves, moss, and pieces of soft rotting wood.
Keep the substrate moist to the touch but not saturated. You should not be able to squeeze water out of it. The surface should be allowed to dry between mistings — it's the substrate depth that holds the humidity gradient, not a permanently wet surface.
The substrate is part of the diet. They eat it. Use quality ingredients, and replace it completely every 6 months to prevent frass accumulation.
Temperature
19–26°C, with the cooler end generally being better. Ardentiella can suffer in heat — prolonged temperatures above 26°C can stress a colony. During UK summers, if your house gets warm, plan for this. Some Ardentiella keepers use wine coolers or climate-controlled rooms during heatwaves.
In winter, most UK houses will naturally sit within the ideal range without additional heating. If your room regularly drops below 18°C, a low-wattage heat mat on a thermostat placed on the side of the enclosure (not underneath) can help.
Diet
The primary diet is leaf litter and white rotten wood — always keep these well stocked. Supplement with vegetables: courgette, baby corn, and sweet potato are reported favourites for Ardentiella. Occasional fruit can be offered. Moss and lichen are both eaten and appreciated.
Protein is important — offer gammarus shrimp, fish flakes, or freeze-dried bloodworm once or twice a week.
Calcium should always be available. Cuttlebone left permanently in the enclosure is the simplest approach. Ardentiella consume noticeably more calcium than many other genera, so keep it topped up.
Remove uneaten fresh food within a day. Mould in an Ardentiella enclosure is something to actively prevent.
Breeding
Captive bred Ardentiella breed at a fair to prolific rate once established. Growth is slow, so don't expect rapid colony expansion. A starting group of 5 gives a reasonable chance of both sexes being represented, though the 10-pack option provides a stronger foundation.
One of the pleasures of breeding Pastel specifically is the colour variation between broods. The pastel palette can shift and vary across generations, so each new batch of juveniles has the potential to surprise you. This makes colony-watching more engaging than with morphs where every individual looks essentially identical.
No special triggers are needed for breeding — consistent, correct husbandry is sufficient. Good ventilation, clean substrate, varied diet, appropriate temperature.
