Thanks guys, the rocks are collected locally, so I guess they are volanic of some sort.
I'm planning to stock the tank with a group of small lampeyes. (either poropanchax myersi or Lacustricola kassenjiensis) They don't really school, but they are constantly courting which should look nice in open layout.
There is Blyxa Japonica in this tank and I was actually thinking of swapping it for something else. I think I need to be a bit more creative in my plant selection as Blyxa is a no-brainer in a tank like this. Can't take too many "easy outs"

any suggestions to what I can use in the blyxa's spot?
The blue background will go. I want to try to shoot the tank with orange or yellow, maybe tomorrow.