parachromis friedrichsthalii

Excuse the horribly footage not sure why the lighting made some appear white. Assuming the largest is a male and is around 3 inches. Not sure on sexing them assuming they need to still grow more. I was in their tank changing some things around not long ago so colours aren’t fully showing

I was growing out a group of these guys last year around this time and ended up with one m/f pair. They were growing well and everything until I lost my male to a choking incident. I ended up keeping the female but without a male for her I decided to give it another try. So I'm growing out...

I woke up to half my tank dead. 1 Parachromis friedrichsthalii 2 Amphilophus Lyonsi 1 Amphilophus Labiatus 1 Amphilophus sagittae I had did a water change 9 days and Added API Quick start yesterday because i didnt have any solution. I followed the instructions to a T. It ended in a massacre.

I have 3 parachromis friedrichsthalii which I'm having trouble identifying sex. One I believe to male kinda keeps everyone of them in check. The first one is the one I believe to be Alpha male. The last pic is the same one as the first one.