I have a few extra tanks and was curious about what kinds of animals could live in them. I’d prefer mammals or lizards no fish, please!
For your 20-gallon, you could consider something like a leopard gecko or a crested gecko. Both are relatively easy to care for, don’t need too much space, and are fun to watch!
For the 40-gallon, you could definitely house a bearded dragon! They’re pretty active lizards and love to bask. Just make sure you’ve got the right heat and UVB setup.
If you’re into mammals, a 20-gallon tank might work for a pair of African pygmy mice. They’re small, super cute, and don’t need a huge amount of space. For the 40 or 75 gallons, you might be able to house a small group of degus or even a couple of sugar gliders, but make sure to check their space needs first!
I’d say for the 75-gallon, you could go with a larger lizard like a blue-tongued skink or even a small uromastyx. Both of them need a decent amount of space but would thrive in that tank size!