Hey pricey! Some plants I suggest you may or may not like but.. Maybe an anubias? If your not into anubias, some Sagittaria sabulata. if you wanted something to thicken out and bush to the top, hygrophila siamensis 53B. I have a nice anubias Gracilis on a small lava rock and bury the rock! I have this plant towards the front of my tank on a dragon stone rock and it looks great! I'm not the best at suggesting plants but these are a few I have in my tank and they are growing in the shade good enough