Thinking that in the future I would like to move the tetras and some of the plants and driftwood from my current set-up (20 tall) to a larger tank and add some other tetras, corys, and possibly some dwarf cichlids along with more sword plants, brazilian pennywort, ludwigia etc. to create a South American (or at least a Western Hemisphere) biotope type set-up.
That would leave the 20 gal with anubias, java fern, and crypts to which I would add more Asian plants, for a Asian/African/Eastern Hemisphere tank. I think I would like to stock this tank with some nano/micro fish.
I'm considering a group of small rasboras (either b. brigittae or maculatus) for the upper level and a group of dario dario for the lower levels. Beyond those I'm not sure. I would like to add a group of slightly larger mid-level swimmers. Would glowlight danios (not glowfish) work here? And some substrate fish to round out the tank. Banded dwarf loaches seem to be perfect, but likely difficult to come by. Would regular dwarf loaches (sidthimunki) work? Any suggestions for something that would fit the bill for either of these? Think barbs, rasboras, danios, rainbows (no tetras) and loaches or catfish other than corys.