You may actually have better luck breeding them in the smaller tank instead of the 20H.
Put the female in the tank and provide her plenty of plants for cover or divide the tank in half with a piece of acrylic. A small sponge filter with very low air flow can be added but you may not need any aeration at all. You don't want the water surface to be disturbed. I add a styrofoam cup cut in half top to bottom as a shelter for the male to build a bubble nest.
After breeding remove the female, After the eggs hatch remove the male. Males only care for fry until they become free swimming. After that, they will prey on the fry.
The reason I recommend the smaller tank is that it is a lot easier to maintain feed density in the smaller tank than the larger one. You need to add a lot more infusoria, microworms, and baby brine shrimp to the larger tank than the smaller one to maintain sufficient density for the fry. That just leads to more waste in the tank and problems with water quality. Once the fry have grown a bit you can move them to a larger tank to grow out.
Andy
Put the female in the tank and provide her plenty of plants for cover or divide the tank in half with a piece of acrylic. A small sponge filter with very low air flow can be added but you may not need any aeration at all. You don't want the water surface to be disturbed. I add a styrofoam cup cut in half top to bottom as a shelter for the male to build a bubble nest.
After breeding remove the female, After the eggs hatch remove the male. Males only care for fry until they become free swimming. After that, they will prey on the fry.
The reason I recommend the smaller tank is that it is a lot easier to maintain feed density in the smaller tank than the larger one. You need to add a lot more infusoria, microworms, and baby brine shrimp to the larger tank than the smaller one to maintain sufficient density for the fry. That just leads to more waste in the tank and problems with water quality. Once the fry have grown a bit you can move them to a larger tank to grow out.
Andy