My last two were about 6" and 4" (male and female) and they did a lot of behavours for about 6 months and never did spawn. It always seemed that they switched back and forth as to which was the more randy

The male would dig a flat spot down to the aquarium floor and dance for the female and she would basically ignore him and then later (like a week or so) she would be the one who seemed "in the mood"

and she would do the dancing and her colors would darken and she'd do the digging and he wouldn't be interested. It probably didn't help that i kept vacuuming the tank and screwing up their carefully made spawning area every week

. I think hands off is the best approach and give them as much space and privacy as possible and they'll be breeding before you know it. Good luck.