If you have a cory, you should:
- Get at least 5 more
- Have sand as a substrate, as cories sift through the sand to scavenge for food, and they have really sensitive barbels, easily damaged on gravel.
I think you should add more plants, maybe even some floating ones? Also some more foreground and backround plants. You could even change to a black blackround, that would make everything stand out more.
Those are just my few ideas, tank looks nice!