I have a pair that are great parents.
The signs for me were both parents developed darker parts of their body, mid abdomen to tail. Kinda stripes. The female's abdomen swelled with eggs, they both dug a nest and laid over 200 -300 eggs. Mom stayed with the eggs and dad guarded the nest. Not that he had to, they were the only fish in the tank.
I wasn't concerned about removing the fry as I really didn't want to raise the babies, but much to my surprise both parents have allowed the fry to thrieve in the same tank! I understand that they will eat their young as they get ready to breed again.
I've had to separate the male and female as he really beat her up when he was ready to mate again and she was not. So, be careful to only allow them to be together when she is ready.
I have moved over 100 fry to a separate tank. They are kinda cute.....goodluck!