It's one of the most common questions we're asked: can you keep millipedes and isopods in the same enclosure? The short answer is yes, usually — the two get on well, want broadly similar conditions, and isopods even earn their keep as a cleanup crew. But "usually" is doing some work in that sentence, because the species you choose and the way you set things up make the difference between a thriving shared enclosure and one where one animal quietly causes problems for the other.
This guide covers when cohabitation works, when to be cautious, which species pair well, and how to set up an enclosure that suits both.
Why it works: similar animals, similar needs
Millipedes and isopods are both detritivores — they make their living breaking down decaying plant matter on the forest floor. That shared ecology is exactly why they're natural enclosure-mates. They want the same things: a nutritious substrate built on leaf litter and rotting wood, stable humidity, calcium, and somewhere to hide. Set up an enclosure correctly for a millipede and you've very nearly set it up for isopods already.
There's a practical benefit too. Isopods make an excellent cleanup crew, grazing on mould, mopping up uneaten food, and processing waste — including millipede frass — into the bioactive cycle. In a well-balanced enclosure they help keep things clean and reduce the maintenance you need to do. If the whole idea of a self-cleaning, bioactive setup is new to you, our roundup of the top terrarium bugs that thrive (or to avoid) in your setup is a good primer on which inverts pull their weight.
When to be cautious
Cohabitation isn't automatic, and a few genuine risks are worth understanding before you combine animals.
Aggressive, fast-breeding isopods can overwhelm an enclosure. Some isopod species reproduce explosively and forage assertively. Species like Porcellionides pruinosus ("powder" isopods) and Porcellio laevis are notorious for breeding into enormous numbers very quickly. In a shared enclosure, a booming isopod population can compete for food and, more importantly, may disturb a millipede while it's moulting — which, as any keeper knows, is the most vulnerable moment in a millipede's life. There are even occasional reports of large, assertive isopod colonies bothering a soft, freshly-moulted or resting animal. This isn't a reason to avoid isopods, but it is a reason to choose calmer species.
Calcium and food competition. Both animals need calcium and both eat the substrate, so in a crowded enclosure they can compete. The fix is simple — provide plenty of everything, which we'll come to.
Tiny millipede juveniles. If your millipedes are breeding, very small juveniles can be vulnerable in a busy enclosure. Many keepers happily run mixed enclosures regardless, but if breeding millipedes is your priority, a dedicated species enclosure removes the variable entirely.
The best species pairings
The trick to successful cohabitation is choosing calm, well-behaved isopods rather than the aggressive colonisers. Good choices are the slower-breeding, less assertive species that potter about cleaning up without causing trouble.
Cubaris are a popular choice for mixed enclosures — they're relatively calm, beautiful, and well-suited to the humid, tropical conditions many millipedes enjoy. If you're drawn to them, our guides to Cubaris soil isopod care and Cubaris isopod care cover their requirements, and species like the Cubaris Amber and Cubaris White Shark are attractive options that coexist nicely with calmer millipedes.
Larger, slower Porcellio and Armadillidium species can also work well, contributing good cleanup without the population explosions of the powder isopods. If you're still deciding which isopods suit you, our pieces on unusual and oddball isopods and five species for something a bit more unusual are good places to browse, and if you're brand new to isopods entirely, start with our complete beginner's guide to keeping isopods in the UK.
On the millipede side, calmer, surface-active species pair best. The big, easygoing African giants — the African Giant Chocolate and Ghana Speckled Leg — make relaxed enclosure-mates, as do the smaller prolific species.
Springtails: the third member of the team
There's a third invertebrate that belongs in almost any bioactive enclosure, and it causes no trouble at all: springtails. These tiny collembolans are the workhorses of a clean setup, consuming mould and breaking down waste at a scale the bigger animals can't. They coexist peacefully with both millipedes and isopods, compete with neither, and quietly keep the whole system balanced.
Adding a culture of springtails to a millipede-and-isopod enclosure is one of the easiest ways to keep it healthy. Ours come in several varieties — including lilac springtails and lilac and yellow springtails — and a starter culture quickly establishes itself in good substrate.
Setting up a shared enclosure
If you've chosen compatible species, here's how to give everyone the best chance.
Go bigger than you would for one species. More space means less competition and more room for each animal to establish its own area. Don't crowd a small tub.
Build a deep, nutritious substrate. This matters even more in a shared enclosure, because it's feeding everyone. Base it on leaf litter and white-rotted hardwood, and make it deep enough for your largest millipede to bury itself completely and moult safely — that depth requirement is set by the millipede, so follow our substrate guide. If you want a deeper dive into building the perfect bioactive base, our article on substrate components for isopods is a useful companion read.
Provide calcium generously. With two calcium-hungry animals sharing the space, don't ration it. Keep cuttlebone available on the surface and mix crushed oyster shell through the substrate so there's a constant slow-release source for both.
Offer plenty of food and hides. Spread food out so animals aren't forced to compete in one spot, and provide lots of cork bark, leaf litter and rotting wood so everyone has somewhere to retreat. Abundance removes most cohabitation conflicts before they start.
Keep an eye on the balance. The main thing to watch is the isopod population. If even a calm species starts booming and you notice them constantly swarming food or bothering a moulting millipede, thin the colony out (they make great feeders or can start a new culture). A healthy mixed enclosure is one where no single animal dominates.
So, should you?
For most keepers, a shared millipede-and-isopod enclosure is a genuine pleasure: a miniature ecosystem that's more interesting to watch and easier to maintain than a single-species setup, with the isopods and springtails handling much of the cleaning. The key is to choose calm isopod species over aggressive colonisers, give everyone a large, deep, food-rich enclosure, and keep calcium and hides abundant.
The one time to keep things separate is if breeding a particular species is your goal — then a dedicated enclosure removes the competition and lets you manage that colony precisely. (If your isopod colony ever does crash, by the way, our colony-crash troubleshooting guide will help you work out why.)
Browse our millipedes for sale, have a look at our isopod range if you'd like to add a cleanup crew, and pick up everything you need from our accessories. As always, our live chat is happy to help you put together a combination that works.
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