Size of the fish is good to start with. One thing you might want to consider is a rock/plant in the middle as a territory/sight break. Sometimes it helps, sometimes not. You could always wait and see on that. Another thing I've found with occies is that males may at first drive all others out of their territory including females when first gettting established. I've also found other small shellies to be the same. You may need to add more hiding places for them, maybe at the ends of the tank. The plant on the left is good, so maybe more of that. You can wait and see, just some ideas for you. I've seen females and sub-males get pushed into corners in bigger tanks. I've seen them get rejected after spawning a time or two and get pushed out. Seems when I had two breeding pair and things were stable, it didn't last long. Very interesting fish when things are going well and they're breeding, just be ready to manage this. Actually a good thing, as it can make the tank more interesting that way. Feels gratifying to change things up and have it actually work out.