Rubber Ducky isopods (Cubaris sp. "Rubber Ducky") are one of the most recognizable species in the US hobby. They are named for the pale face and dark eye spots that look like a little duck bill. They come from cave regions of Thailand and are a favorite of both collectors and bioactive keepers. This guide covers everything you need to keep a colony healthy and breeding.
Rubber Ducky Isopod Quick Facts
- Scientific name: Cubaris sp. "Rubber Ducky"
- Origin: Thailand
- Adult size: 1.2 to 1.8 cm
- Care level: Intermediate
- Temperature: 72 to 80°F
- Humidity: 70 to 80% on the damp side, with a drier side
- Ventilation: Moderate, cross ventilated
- Breeding rate: Slow to moderate
- Activity: Nocturnal, burrowing
- Lifespan: Commonly reported at 2 to 3 years
Enclosure Setup
A 6 quart bin with cross ventilation (holes or mesh on two opposite sides) works well for a starter colony of 10 to 20. Give a growing colony more room over time.
Rubber Duckies burrow, so give them 3 to 4 inches of substrate. We use our own ABG style mix in every bin: 12 parts sphagnum moss, 6 parts coco fiber, 4 parts orchid bark, 2 parts charcoal, and 2 parts worm castings. The full recipe is in our ABG substrate guide.
On top of the substrate, add:
- A thick layer of hardwood leaf litter, topped up as it gets eaten
- Decaying hardwood
- Cuttlebone for calcium, available at all times
- A culture of Tropical Pink springtails to keep mold and leftovers in check
- Cork bark for hides
Humidity and the Moisture Gradient
Keep one side damp and the other drier. Mist the damp side every few days, or whenever the surface starts to dry, and never let the whole bin dry out. Good airflow matters just as much as moisture. A wet bin with stale air invites mold and mites.
Many keepers also refresh part of the substrate once a lot of it has turned into frass (isopod droppings), since heavy frass buildup can sour a bin over time.
Temperature
Keep Rubber Duckies between 72 and 80°F. Normal room temperature works in most homes. Keep them out of direct sun and away from heaters.
Feeding
Leaf litter and decaying hardwood are the base of the diet and should always be available. On top of that, we rotate small amounts of fish flakes, freeze dried shrimp, and occasional soft vegetables like zucchini or carrot. Offer a little at a time and remove leftovers within a day or two.
Keep cuttlebone in the bin at all times. Rubber Duckies need steady calcium for clean molts.
Breeding
Rubber Duckies breed slower than common cleanup crew species. Stable conditions, steady calcium, plenty of leaf litter, and minimal disturbance are what keep a colony producing. A settled colony of 20 or more adults will produce young consistently through the year.
Are Rubber Duckies Good for Bioactive Setups?
Yes. They make a great display species in a humid planted terrarium of their own. Avoid dry enclosures, since Rubber Duckies need consistent humidity to survive.
Common Problems
- Colony will not breed. Check humidity, calcium, and how often the bin is being disturbed.
- Isopods dying during molts. Usually low calcium or a bin that is too dry. Add cuttlebone and keep the damp side damp.
- Mold. Some mold is normal in a new setup. Springtails help a lot. Persistent mold usually means not enough airflow.
Common Questions About Rubber Ducky Isopods
Are Rubber Ducky isopods good for beginners?
They are intermediate, but they are one of the more forgiving collector Cubaris. With stable humidity, airflow, and calcium, most keepers do well with them.
How big do Rubber Ducky isopods get?
Adults reach 1.2 to 1.8 cm.
What humidity do Rubber Duckies need?
Around 70 to 80% on the damp side, with a drier side so they can choose.
How fast do Rubber Duckies breed?
Slow to moderate. A settled colony produces steadily, but expect a new group to take a few months to get going.
Where to Buy Rubber Ducky Isopods
All Rubber Ducky Isopods at Creature Cache are captive bred and ship FedEx Priority Overnight with a 100% live arrival guarantee. Shop Rubber Ducky Isopods and pair them with a Tropical Pink springtail culture, or join the Creature Club for restock alerts and 10% off your first order.
More reading: How to Set Up Your First Isopod Enclosure, our ABG substrate recipe, and our springtail care guide.
Questions about your animals? Email us anytime at info@creaturecache.com.