I know of one person that does use it for geckos. I believe they coat it with a sealant first. Just make sure you stabilize it well, or you'll be hearing a lot of thuds.
Cause when push comes to shove you taste what you're made of
You might bend, till you break cause its all you can take
On your knees you look up decide you've had enough
You get mad you get strong wipe your hands shake it off
Then you Stand
A non toxic water based clear polyurathane (clear coat) should do the trick quite nicely. Just let it cure before you put it in there as those fumes can be pretty intense.