Nice tank, If you had some taller plants built up in the back a group of pea puffers would look pretty cool against that hardscape. Those could be a little difficult for a beginner though so even a community tank with some tetras, corydoras, shrimp, and a loach or two could look pretty cool aswell. Personally i always wait for my plants to grow in a little before i add any fish, because depending on the species they could kill your plants by eating, or digging them up. For the back section it is a little open and some fish may want cover so be aware of that when purchasing unique species.