My lfs always has diamond Tetras onhand, and they are absolutely gorgeous. It's as if they were rolled in giant hologram sequins. Like many fish, they look at their best when natural light bounces off them.
I did watch quite a few vids on the Rummynose tetra, and I simple must have some - lol I have a total of 4 tanks to fill, so two have now had fish selected ; )
Apparently Odessa Barbs prefer cooler water - in the mid 60s to low 70s - will the Rummynose Rasbora fit that requirement? maybe you could have both...