Corn snake & crested gecko in same room

Reptile welfare is almost entirely determined by getting the environment right — temperature gradient, UV lighting, humidity, and substrate all need to match each species' natural habitat, and getting it wrong causes chronic stress and illness over time. You've actually got one of the trickiest room-sharing combinations: corn snakes want fairly dry conditions (around 40–50% humidity) while crested geckos need it quite moist (70–80%). Before I give you a practical solution, tell me — how old are each of your animals, and are you setting these enclosures up fresh or trying to fix an existing problem with humidity bleed between the two?

That's almost certainly the issue. Sustained ambient humidity of 60–65% is genuinely too high for a corn snake long-term — it can cause respiratory infections and scale rot, especially if the substrate stays damp. The gecko's misting is doing exactly what it should for him, but the moisture is just hanging in the shared room air. A few things to address this: first, you need accurate per-enclosure humidity readings rather than relying on room feel, and second, you want to manage airflow so the gecko's humid microclimate stays contained. Can you tell me what ventilation the two enclosures currently have — mesh tops, glass sliding doors, that sort of thing?

Right, the mesh top on the Exo Terra is your biggest culprit — it's designed for airflow but that means the moisture you're putting in is also escaping straight into the room. You have two practical fixes working together. For the Exo Terra, get a partial mesh cover — a simple cut piece of glass or perspex over roughly half the top massively reduces moisture escape while still allowing adequate ventilation for the gecko. For monitoring both enclosures properly, I'd recommend the Zoo Med Digital Hygrometer and Thermometer — it's a dual-probe unit so you can track humidity and temperature inside each enclosure simultaneously without guessing at room averages. That way you'll know in real time whether the corn snake's enclosure is actually sitting at 45% or creeping up. It's around £15–20 on Amazon UK and is genuinely the most reliable entry-level unit for this job. For the corn snake vivarium itself, close the side vents down a little to reduce the draw of humid room air inward.

Only as a last resort, and honestly probably not necessary here. If you partially cover the Exo Terra's mesh top, the room humidity will likely drop back to a comfortable 50–55% on its own — which is fine for the corn snake's ambient air as long as her enclosure internals are managed correctly with the right substrate (aspen or beech chips, never coconut fibre). A room dehumidifier also risks dropping the humidity too low for the gecko if the Exo Terra seal isn't perfect. Get the Zoo Med dual probe unit in first, make the mesh cover adjustment, and monitor for a week. You'll almost certainly see the corn snake's enclosure readings normalise without any additional equipment.

Good plan — and keep an eye on the corn snake over the next two to three weeks once humidity normalises. If she had any early respiratory involvement you might notice some improved activity and feeding response fairly quickly. If she's still looking lethargic or has any wheezing or mucus around the mouth after the environment is corrected, that warrants a vet visit rather than waiting it out. But in most cases like this, fixing the humidity is all it takes.