20 Gallon Paludarium for some kind of gecko?

[dinodeep]

Hi I am a student who is making a paludarium (half water and half land) for a school project. The problem with this is I really want a lizard that meets the following requirements:

-Nocturnal (so no UVB!)
-Can swim (water is 8 inches deep)
-Won't eat fish
-Can live in 20 gallons (essentially 10 with the water)
-Price does not exceed 30 dollars (I live in Canada by the way)
-Not a crested gecko (My classroom already has one)

I was thinking of getting a leopard gecko, but they don't really suit the environment well. So I don't really know what lizard to go with. Any suggestions?
Here is some pictures of the tank: https://drive.google.com/open?id=0Bx...1g1aU5IM2F2OGc

Thanks in advance!