The 55 is gravel. I used pool filter sand in the 15 just for the loaches, also I think the loaches would eat the cherry shrimp. I would not look forward to trying to catch cherry shrimp in a heavily planted tank.
Heres a pic, I added some narrow leaf java fern from the 55 with the wisteria from the 75.
Built a couple of caves and this is what it looks like.
I don't know if the glass is scratched, I don't see scratches or if the camera lens some how got scratched, hopefully its just dust as i didn't clean it off before the pic, but ignore the ugly white lines.
I'd suggest a small school, like cherry barbs, tetras, or rasbora... maybe 4-6, and then a clean up crew, either a few corys or otos, maybe a snail. give it room to breathe and grow.