Its great to hear that you dtarted paro aquaristics and I hope you and your fish will be doing great. At least some of the fish in your pictures are still rather young. Once they mature completely and color up more they will be more easy to determine. How many fishes do you have?
I think that indeed in some of the pictures one of the females shows “sexy eyes” – the vertical black line theough the eye. If this intensifies and the flashing of the male becomes more frequent, they will soon build a nest. However you mainly need to focus on feeding now so that the females will soon grow eggs…
Greetings Rafael