Lots of stuff would fit, you just have to think non-monster. There's small geckos like knobtails or the African velvet species that would be more than happy with that, or a large tarantula like a Chaco or salmon birdeater. Also maybe a garter snake. Mine is going in my 12 gallon once he outgrows the 5. Then there's things like scorpions such as flat rocks or emperors that would make great displays. Also if it is a 12 finding a screen lid shouldn't be a problem. A 12 is roughly 24x12x12 I got a lid for mine at the lfs and it has locks and light clips

there's tons of stuff that will fit. Pm me if you want more ideas
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