feed blood worms worms and live foods and pre condition them, then as joe said do a water change with slightly cooler water, the cooler water replicates nature when in the wild there is rainfall and the slightly cooler water from the rain falls into the streams and rivers witch makes the water cooler which encourages them to breed because they think that the cooler water means rain and when it rains the rivers swell and get bigger and more water = more fish so yeah, substrate doesn't matter since in the aquaria they lay eggs on the sides on the glass. i cant get my cories to stop breeding lol every 4 weeks i get some eggs on the glass i just, let my other fish eat them, a nice little treat for them!