Mollies are members of the Poeciliidae family, which includes other livebearer species such as guppies and platies. They belong to the genus Poecilia, which contains several species of mollies, including the sailfin molly (Poecilia latipinna), the black molly (Poecilia sphenops), and the yellow molly (Poecilia flava).
Each species of molly may have different population sizes and geographic distributions, but collectively they have a significant global presence due to their introduction to numerous bodies of water worldwide. However, it's worth noting that their population dynamics can fluctuate over time, and new populations may emerge or existing ones may decline based on various environmental and ecological factors, including habitat quality, predation, and competition with other species.
In summary, while the precise number of mollies on Earth is difficult to determine, they are widely distributed and have established populations in various freshwater habitats across different regions of the world. Their presence is influenced by factors such as species adaptability and human intervention through the aquarium trade and intentional or accidental releases into natural water bodies.