Help With Red Top Zebra Sexing Please?

Hey again!
Ok so I have a 55g mbuna tank w/yellow labs, m. greshakei (ice blues) and m. pyrsonotos (red tops), first off is this a decent mix for a while (prob till I can afford to convert to an all male tank, maybe in a 75g+ so maybe up to a year or so). My blues and yellows are each breeding within their respective groups regularly.
As far as the red tops, I got 2 a few months ago when i was getting neat fish from the mixed african tanks and didnt know any better lol, and I so wound up giving many incompatible oddball fish to friends with large tanks and some back to the lfs. So those 2 which I kept are now mature (i think) at a lil over 3", ones colored up dominant and fighting the dom yellow and blue, and the other red top is much darker than the dom, but kind of acts like a subdominant male, im not sure?
So I got 5 more red tops from a lfs, hoping that would be enough for some females and I would have a 3rd group breeding, and dont think I got any lol? The newer ones i have had for a lil under a month, they are about 1.5-2", and are all dark and dont look very good at all. I looked at all the pictures in the species article here and didnt see any pics of females, so i was wondering if anybody who has/does own these fish could help me out? Are they like the labs that all look basically the same, or like the blues that look diff. ect, how do u tell etc? Thanks again everybody!! Help and advice appreciated as aways!!