I don't have photos on me but my parameters are 0 amonia 0 nitrite 10nitrate and my temp everyday is 26C but one of them is bigger than the other and has black on the top and bottom and the smaller one has no black on top or bottom but it use to have some black on top
Okie, sounds like a male/female. You can try replacing 20-30% of the water with water that is 2-3 degrees cooler than your tank water. That could induce spawning.
But really, it's up to them when they want to spawn, there's not really much you can do. I've had multiple proven breeding pairs they actaully never bred together until almost 6 months-year in. It really depends on them.