I once brought seven young convicts from a lfs at a young age. Some with orange bellys some not. A few weeks later after bringing them home i was suprised to see they all showed orange bellys. 7/7 females, what are the odds? Anyway fast forward a few months i get back from a 3 week holiday to find a pair had bred! And dad lost his orange belly..
I did notice some of the fish were growing much faster than the others. One of which ending up being dad to the fry. I guess can never be sure of Convicts genders.