So i've recently come across a few sources that say oriental fire bellies can be kept with other animals? I had just assumed that they couldn't. If not then I would like to get some. I have a small (5'' including tail) nocturnal arboreal fish-scaled gecko that eats dusted crickets. She lives in a 45cm x 45cm x 45cm palidaerium. The the bottom third is split 50/50 into land and water, with a filter and an airstone. The pond contains roughly 2 gallons of water. The other two thirds heavily planted, with a thick canopy of branches. Its kept at around 25 degrees C, uvb is provided.

I love my gecko very much but she is very cryptic and I barely ever see her. I would love a more active species for the tank.
Would this be too small to keep them together?
What if i were to upgrade to a taller tank, would it then be possible?
If fire bellies are not appropriate, if there another amphibian that might be?

I do not want to put my gecko in danger, she comes first!

Thanks in advance