Is my fish pregnant?

hi, I got some fish a few weeks ago and there are 3 female and 1 male all of the females seem to be larger than they were but one of them for the last 3 days has stayed low under one of the plants is she laying eggs??

well I had 3 fish it killed all of the males and she was doing what your fish did then in a couple of weeks she got big that night I went to go get some water she was dead but there was little baby fish in the tank