Possible pair forming (P. sp east coast small spot)

[foxy]

hi, until just now I was referring to these as polleni, but I´ve just read that they are actually Paratilapia sp. east coast small spot - is that correct?
Anyway, I bought 6 juveniles here in Spain about a year ago, and have been growing them out in a 375 litre, 150cm tank with malawis. They were growing well, and no serious fighting. Then I decided to buy an extra aquarium to have more room for my malawi fry. When I arrived to collect the aquarium, I discovered it came with a "free" Heterotilapia buttikoferi measuring about 30cm. Apparentl he was "my" problem now. He´s a beautiful fish, and I imagined I would have no problem giving him away.....hahaha...funny. Two problems with that theory. 1. Most people don´t want a giant predator that is hard to keep with other fish....2. I started getting attached to him myself. So I rearranged things and gave him the big tank, and moved the Paratilapia into the new aquarium on their own. That´s when the fighting got more serious and I ended up losing one of them, and having to split them up into 3 different tanks to stop them killing each other. 3 of them were left in the new tank, with a divider to keep one on one side, and the only two that didn´t fight on the other side. The two that weren´t fighting were on the small side, and I have made the presumption that theyare both females. One of them started making eyes at the larger fish on the other side of the divider, so last night I decided to remove the divider....and this is what happened...

https://youtu.be/b8Se33q9zH8

Unfortunately, towards the end of the evening the "female" was showing signs of exhaustion, so I replaced the divider to give her a break.

So, advice please. Do I remove all the other fish and keep removing the divider until they get down to it? Would you say they are most likely a pair, or is there still a chance they could be the same sex?

Many thanks for any help you can give me. Although I have bred many different types of cichlid before, I have never got this far with Madagascans.