Any ideas on how to use a little tank ?

[Gooey]

I have a little 12 x 8 x 8 tank, and was looking for some ideas to fill it up.
I know this is a tropical site, but i would also appreciate coldwater ideas too.
I was thinking about moving my betta and red claw crabs to it, but they look happy enough where they are. Or one of those 1/3 land 2/3 water frog/crab "mini terrain" thingies ( a pic/link would be useful too)
Any ideas the more unusal the better
thanks in advance

 

[Davy Reynolds]

There is loads of tropical fish that can live in colder waters. Though if your wanting goldfish your a bit limited due to size anyway.

 

[Rivulus]

I have a large number of small (2.5 gal) tanks that I use for breeding killifish. A pair of small to medium size killies will do just fine in such a tank.