try increasing the temperature just a little..or feeding live foods would pretty much trigger spawning or w/e....u have to be kinda careful because the parents will eat the eggs...u can maybe get some spawning grass , but when after spawning, it's best to remove the parents and like isolate them...i unno if u have experienced this but u can get this fish called Bitterling who like basicly is like a sheild for the eggs and like defends them...