Merulanella sp.
High-end collector isopods from Southeast Asia — spectacular colour forms, but demanding tropical care.
About this species
Merulanella is a genus of isopods from Southeast Asia, increasingly popular in the hobby for their spectacular colouration. Multiple colour forms are traded — including "Tricolour", "Scarlet", "Blue Velvet", and others — often at premium prices. Their bright, saturated colours make them among the most visually striking isopods available.
Merulanella species are terrestrial crustaceans that breathe through gill-like pleopods. They require stable tropical conditions — high humidity, warmth, and excellent ventilation simultaneously. This is an advanced genus. If you have not successfully kept Cubaris murina or similar tropical species, gain that experience first before investing in Merulanella.
Enclosure
A well-sealed plastic tub with controlled ventilation is essential. The same challenge applies as with Cubaris: high humidity must be maintained alongside sufficient airflow to prevent mould and stagnation. Merulanella species tend to prefer slightly warmer conditions than Cubaris (24–28°C), so placement near a gentle heat source may be necessary in cooler rooms. Furnish with cork bark, sphagnum moss, dried leaves, and cuttlebone.
Substrate
- 50% coco coir
- 20% organic topsoil
- 15% sphagnum moss
- 15% crushed limestone or calcium powder
Keep consistently moist but never waterlogged. A moisture gradient is beneficial but the entire substrate should stay damp. Depth 5–8 cm. Top with dried hardwood leaves and sphagnum moss. Never use softwood (pine, cedar) — toxic to all isopods.
Feeding
- Dried hardwood leaves (oak, beech) — primary food source
- Cuttlefish bone — leave permanently; essential for calcium
- Small vegetable portions: courgette, carrot, sweet potato
- Weekly protein: dried shrimp, fish flakes
- Bee pollen — widely used as a supplement for tropical isopods
Remove uneaten fresh food within 24 hours. At the temperatures Merulanella need, food spoils quickly and mould spreads rapidly.
Breeding
Merulanella species breed slowly compared to temperate Porcellio or Armadillidium. Females carry small broods, and new mancae appear infrequently. Building a colony is a long-term commitment. Start with at least 10–15 individuals to give the colony a viable breeding population. Expect years rather than months to build significant numbers.
Common mistakes
- Treating them like temperate species — Merulanella need fundamentally different conditions than Porcellio or Armadillidium
- Letting temperature drop below 22°C — they are tropical animals and will decline in cool conditions
- Inadequate ventilation — high humidity without airflow creates the mould and bacterial problems that kill tropical isopods
- Disturbing the colony too often — minimise handling and substrate disturbance