Silver Lyretail Molly Medium Poecilia Mollies are very closely related to the guppies and are both members of the same genus, Poecilia. Also included in this genus are the platys. Most mollies that are sold are found in Central America and the southern part of the United States. They can be found as either shortfin or sailfin mollies. The shortfin is smaller and the sailfin is bigger. Male mollies have larger dorsal fins than females. Shortfin mollies: The color on these fish is a greenish/silver with some brown and yellow patterns on them, along with the black spots that will vary. Keeping the tank warm will keep these fish happy. In the wild, you would see them in warm springs and ponds, with some weeds. They feed on both plant and animal matter but are mostly herbivores.