I've figured out how to tell the sex of my endlers before they mature and show their colours

@caccoon I remember watching their mating game. I sometimes felt for the girls, there would be three to four men chasing anyone of them at almost any given time. My tanks slightly small to put a divider in and thankfully, the guppies which can explode in population (almost same species), endlers are essentially a rare guppy, that's not happening - yet - this time.

@SW-User yeah the men can be asses. I typically sell them 1M 2F ratio

@caccoon Good idea, I've heard some fish stores suggest 1- 3 ratio to help the girls.