However, fish of the same species have been found in coastal sea waters, brackish swamps and freshwater streams, living and breeding. Mollies appear to be a hardy and highly adaptable species (this has been diluted over years of interbreeding in tank-bred specimens).
Mollies are similar in appearance to their livebearer cousins, the platy and swordtail, although the molly tends to be slightly larger and more energetic. Many aquarists note the stronger individuality and aggression in keeping mollies versus platies, who appear much more docile.