With a tank like this I would do one of two things.
1) A lot more wood in that tank with small fish that like to explore the wood. Endlers are great for this as would be a betta. With the wood you can really take advantage of the height of the tank. Ignore any pieces that are too thick. Pieces skinnier then your wrist are what you would ideally want with lots of branching.
Then on the bottom of the tank you can put 1 really big plant like a lace plant with lots of epiphyte plants growing on the wood (buce, anubias, java fern, etc)
Leave the substrate open and sandy and have a few dwarf corys down there.
2) Because of the height this is a pretty good aquarium for a paludarium. I have never done one of these but I have seen a few in videos. You would be halving your water volume of course and would have to adjust your filtration, but it can be done and would certainly be a very different from your current setup. You could put a few smaller fish in the remaining space and grow terrestrial plants on a small land portion in the back of the tank.