Regalblue, I was going to say, "out of the 30+ Mbunas in my tank, she was the only one that stumped me using the color & fin shape". But I'm glad I caught myself before I put my foot in my mouth!!! Cause I'm still having a hard time determining/guessing at the sex of 2 of my Lion Mara Rocks! 😳Color, fin shape, and even behavior is not helping in that case. I could catch them and vent, but I'm ok not knowing. But YES, venting is best way to sex fish.
All that being said....the "color & fin shape guess" works ok. (Yeah, I know, I know. And I might not think that for long either.) However, I don't know if I would trust it if I was trying to pick out much needed females. But with 8 of each species in my tank, I'm not sweating it if I get it wrong.