To promote breeding, maintain your fish in a perpetual "Spring" light cycle regime, with a daily cycle of 14 hours of light and 10 hours of dark. An easy way to do this is to control the lighting of your tank with a tank light plugged in to a simple interval timer, easily purchased at a hardware store. Place your tank in a quiet place and, if necessary, you can cover it with black plastic sheeting to minimize exposure to outside light. It is not necessary to control the light cycle in this way when you do not need the fish to be breeding. Begin the cycle at least a week before you want the fish to begin to breed again.