We have 3 female black mollies. 2 black ones which have turned a bit silvery/whiteish. Originally, we had one male which had the same colour, but we noticed it will be dying soon (swimming upside down time and again). We added a new male (completely black). It got harassed by the other male, which died within a handful days.
Now, with the new male and 3 females, I notice the male acts normally towards the black ones. However, the silvery one (colored similarly to the dead male, with her lower fin being very dark on the outer part that makes it look similar to the male's part if you don't look closely) gets permanently attacked by the male and chased through the aquarium. He also makes dominance shows as if she was another male.
Is there anything we can do to resolve the situation without one of them dying?