I have recently had two 40g breeder tanks come into my possession for free. And I have this inkling desire to PUT SOMETHING IN THEM.

Guys, you are the best thinkers. What kind of species would do well in a 40g tank?
I was thinking of either:
-Some species of lizard or skink (possibly a pair of smaller species that would live together or a single larger species)
-A species of land tortoise.

I want them to be happy with a 40g tank through adulthood, so probably smaller species.

What do you guys think?