Someone on this forum had ruby barbs, those were fun and beautiful. They are a bit bigger though, so 35 would be a bit much I think. Green neon tetra (simulans) is pretty and extremely long lived, I've still got 4 in I got in 2015, I used to have 20 and I loved their group behaviour, much tighter then regular neons or kardinals. 35 in this tank would look great. If you're unsure about numbers start with 25 first, add the final 10 later?