Yellow Pastel Isopods (Ardentiella sp.)

Yellow Pastel Isopods are a selectively bred Ardentiella morph featuring soft, butter-yellow to golden colouration against darker body segments. Like all Ardentiella, they're Vietnamese natives with active personalities, climbing abilities, and specific care requirements that place them firmly in the "advanced keeper" category. At £200–£750 depending on quantity, these are investment isopods—beautiful, but demanding of keepers who understand what they're taking on.

Species Information

• Scientific name: Ardentiella sp. "Yellow Pastel" (formerly Merulanella)
• Common names: Yellow Pastel Isopod
• Origin: Vietnam (selectively bred morph)
• Adult size: 18–20mm
• Difficulty: Hard
• Rarity: Very rare

Taxonomy Note

This species was previously classified as Merulanella but has been reclassified as Ardentiella following taxonomic revisions. You may encounter both names in older sources and online discussions—they refer to the same group of isopods. Care requirements are identical regardless of which name is used.

Appearance

Yellow Pastel Isopods display soft yellow pigmentation ranging from pale butter tones to more intense golden yellows. The yellow contrasts against darker segmented body sections, creating a striking visual effect. Individual variation exists within the morph—some specimens lean toward softer pastel shades, others display more saturated yellow colouration.

The "pastel" designation refers to the softer, less intense quality of the yellow compared to bolder morphs like Yellow Phoenix. It's a subtle but distinct aesthetic difference that appeals to keepers seeking a more delicate colour expression.

Adults reach 18–20mm, making them substantial enough to appreciate their patterning while remaining manageable in captive setups.

Behaviour

Ardentiella isopods behave quite differently from most genera:

• Active day and night: Unlike strictly nocturnal species, you'll see these isopods moving around during daylight hours as well as at night
• Arboreal tendencies: They climb—a lot. They'll scale enclosure walls, branches, cork bark, and any vertical surface available
• Surface dwellers: Not burrowers. They congregate in leaf litter and under bark rather than digging into substrate
• Social grouping: Often found in small clusters of two or three individuals
• Escape artists: Can climb smooth plastic and glass surfaces, making escape-proof enclosures essential

This active, visible nature is one of the main appeals of Ardentiella. You'll actually see these isopods regularly, which isn't true of many species that spend their time buried or hiding.

Enclosure Setup

Container Security

This cannot be overstated: Ardentiella can climb smooth vertical surfaces including plastic and glass. Juveniles and mancae (newly released young) are particularly adept escape artists. You need:

• Completely escape-proof enclosures with tight-fitting lids
• Fine mesh over ventilation holes (large enough for airflow, small enough to contain mancae)
• No gaps around lid edges or vent openings
• Consider petroleum jelly barriers around the upper rim as additional security

Lost isopods at £40+ each is expensive—secure your enclosure properly.

Ventilation

Critical for Ardentiella. They need high humidity but are sensitive to stagnant air. The combination of moisture and poor airflow leads to mould problems and stressed colonies. Provide:

• Multiple ventilation points (3–4 openings minimum)
• Cross-ventilation where possible
• Mesh-covered vents that allow airflow while preventing escapes

Substrate and Layout

Create a layered setup similar to Cubaris enclosures:

• Moisture-retaining base layer (organic topsoil, sphagnum peat moss)
• Substrate should be moist but not waterlogged—high air humidity, not wet soil
• Decaying leaves layered on top
• Forest moss throughout
• Twigs with lichen attached
• Cork bark or tree bark pieces on top

Because Ardentiella are climbers, provide vertical structure:

• Tall enclosures work better than wide, shallow ones
• Cork bark positioned vertically
• Branches and climbing surfaces at multiple levels

Temperature

• Range: 19–26°C (66–79°F)
• Optimal: Around 20°C—average UK room temperature works well
• Critical: They prefer cooler conditions than many tropical isopods
• Warning: Temperatures above 26°C cause stress and can lead to rapid colony decline

This is important to understand. Despite their Vietnamese tropical origin, Ardentiella don't like heat. Keeping them too warm is a common mistake that kills colonies. If your room regularly exceeds 26°C in summer, you'll need to manage temperatures or consider whether these are the right isopods for your setup.

Humidity

• Range: 60–75%
• Substrate: Moist but not saturated
• Air: High humidity with good airflow—this balance is key
• Maintenance: Regular misting to maintain levels

The challenge is maintaining high air humidity while ensuring adequate ventilation. Stagnant humid air is dangerous; fresh humid air is what they need. It takes some adjustment to find the right balance for your specific setup.

Diet

Ardentiella have varied dietary requirements:

Staples:

• Aged leaf litter (oak, beech, maple)
• Rotting white wood
• Forest moss
• Lichen (on twigs or bark—they seem to particularly enjoy this)

Fresh foods:

• Vegetables: carrot, sweet potato, courgette, squash
• Fruits: offered sparingly
• Leafy greens

Supplements:

• Protein 2–3 times weekly: fish flakes, dried gammarus shrimp, protein powders
• Calcium: cuttlebone, crushed eggshells, oyster shells, limestone
• Kinshi (fungus-colonised wood substrate)—an alternative to plain rotting wood

Avoid:

• Bee pollen—Ardentiella reportedly don't eat it
• Leaving fresh food to mould—remove uneaten items promptly

Breeding

Yellow Pastel Isopods can breed at moderate to prolific rates once established, but success depends entirely on maintaining correct conditions consistently:

• Stable temperature within the optimal range (around 20°C ideal)
• Correct humidity balance with good ventilation
• Varied diet with adequate protein and calcium
• Minimal disturbance—leave established colonies alone

Captive-bred specimens generally reproduce more readily than wild-caught. Females carry eggs in a marsupium before releasing fully-formed mancae. The young inherit colouration from birth, though intensity may develop further through successive moults.

Reproduction rate: Moderate to prolific for captive-bred stock under good conditions.

Why They're Challenging

Yellow Pastel Isopods are rated hard difficulty for legitimate reasons:

• Temperature sensitivity: Too warm and they decline—this catches people out
• Ventilation balance: High humidity plus good airflow is tricky to maintain
• Escape ability: They climb smooth surfaces; inadequate enclosures mean lost isopods
• Price point: At £200 for 5, mistakes hurt financially
• Availability: Very rare—replacing losses isn't always possible

These aren't beginner isopods. They're not impossible, but they require attention and understanding that forgiving species don't demand.

Care Summary

• Temperature: 19–26°C (prefer cooler end, around 20°C)
• Humidity: 60–75% with excellent ventilation
• Substrate: Moist but not wet, layered setup with vertical structure
• Ventilation: Critical—multiple openings, avoid stagnant air
• Diet: Leaf litter, rotting wood, moss, lichen, vegetables, protein 2–3x weekly
• Calcium: Essential—cuttlebone, eggshells, oyster shell
• Behaviour: Active day and night, arboreal, climbers
• Escape risk: High—can climb smooth surfaces
• Breeding: Moderate to prolific when conditions are right

Pricing

• 5 isopods: £200
• 10 isopods: £400
• 20 isopods: £750

Who Are They For?

Yellow Pastel Isopods suit:

• Experienced keepers: Those who've successfully maintained other tropical or Ardentiella species
• Collectors seeking rare morphs: The yellow pastel colouration is distinctive and desirable
• Keepers who want visible isopods: Their active, climbing nature means regular sightings
• Those with controlled environments: Stable temperatures below 26°C year-round

They're not suitable for:

• Beginners without prior isopod experience
• Anyone expecting low-maintenance keeping
• Hot rooms or environments exceeding 26°C regularly
• Keepers who can't invest in proper escape-proof enclosures

Bioactive Use

Ardentiella can work in bioactive setups, though their requirements are specific:

• They don't damage healthy plants—safe for planted terrariums
• Their arboreal nature means they occupy different niches than ground-dwelling species
• Can coexist with other cleanup crew species
• Temperature requirements must be compatible with any reptile/amphibian inhabitants
• Escape prevention remains critical in bioactive enclosures

They're not the most practical bioactive choice given their price and requirements, but they can function in appropriate setups designed with their needs in mind.

Related Morphs

If you're interested in Ardentiella, other morphs to consider include:

• Tricolor: The "base" morph with red, yellow, and black colouration
• Scarlet: Enhanced red pigmentation
• Yellow Phoenix: Bolder yellow and black banding
• Pink Lambo: Pink and yellow expression
• Pink Lemonade: High yellow morph developed from Scarlet
• Blister: Distinct colour pattern from Tricolor lineage

All Ardentiella morphs share similar care requirements, so experience with one transfers to others.

Yellow Pastel Isopods offer stunning aesthetics and genuinely interesting behaviour for keepers ready to meet their needs. They're demanding, but the combination of soft yellow colouration and active, visible personalities makes them worth the effort for those prepared to provide proper care. Just don't underestimate the challenge—or the escape risk.