Contrary to popular belief that these fish are a brackish water species that prefers some salt in their tank, this species of fish is actually a freshwater species spending little time in brackish water before swimming back to their freshwater bio-type. However, fish of the same species have been found in coastal sea waters, brackish swamps and freshwater streams happy and breeding. It appears Mollies are a hardy and highly adaptable species (this has been diluted over years of inter-breeding in tank-bred specimens).