A: Sounds like your females are in a community tank. You have a problem with either your water or a pathogen. As always with any community tank situation you must immediately remove any fish that is not acting normal. For three reasons: 1)- that other healthy fish do not become infected 2)- to medicate the sick fish  3)- to prevent the sick fish from being picked on by the others.

Check your water parameters (temp, PH, especially nitrite, chlorine and ammonia levels). If all looks good, then you are looking at a bacterial infection, possibly one of the real tough ones (kill fish fast and not many outside signs, except for the fish just floating there with clamped fins and soon dying). This can be very contagious. Remove affected fish and treat with Kanacyn (double the dose). If more than 2 fish in the tank are affected, you must treat the whole tank also even of the rest of the fish 'look' OK. 

If you are currently feeding live foods, discontinue. Stick to frozen and freeze dried (less prone to bacteria).