If you want to encourage them, it's a good idea to start by feeding them lots of live food, frozen or jellied will do, plenty of it. Then after a few days of this do a water change and add slightly cooler water- simulates the onset of the rainy season in the Amazon which is the time of year when they breed. If you want to make it extra lifelike you can "rain" the new water down on them with a (new) watering can. I don't think there is any need to flash a torch at them and shout bang bang (though my husband did).
To rear the fry, you first need to make sure the parents (or other fish) don't eat the eggs. This is the one I've never managed. Then they need to be transferred to a rearing tank with good oxygenation. They hatch in about 4 days, I think, and then take an extra few days to consume their yolk sac before you need to start feeding them.
Mine started spawning just before they reached adult size.