What to do with an empty 10g

I've been off the GFF board for a while since I moved but now that the tanks are settled and the boxes are mostly unpacked I'm starting to wonder about what I should do with my empty 10g tank.

I have a 29g that's almost completely stocked and an 8g hex that is stocked. The 10 was housing some fry but all but one were lost and the lone survivor is now in the 29. that leaves me with a lonely, empty 10 begging to be filled. I guess I could do the prudent thing and keep it as a standby hospital tank but prudence is boring

I'm looking to do something interesting and fun with this tank. I'm open to a brackish water tank with crabs or some other brackish fish. I could do frogs or maybe a dwarf puffer tank ( I certainly grow enough snails in my other tanks for them.) Maybe a crayfish tank?

What are your ideas? I still have a bunch of playsand and would use that as a substrate and I have a heater but I would have to buy a filter.

Tom

Newts are a thought! They could definitely be cool in there.

Already done the fry tank thing and it works out to be more of a pain than its worth for me. I don't have the room to add the fry anywhere when they're done and my work schedule doesn't allow for proper feeding so I find myself spending a lot of time cleaning the tank.

I really like the idea of something a bit different. I could almost go for some sort of tidal marsh type of setup. That's why I brought up the crabs. Any small brackish fish that could deal with a small tank? Could crabs be added to or is this an either or thing?

Tom