Types of Molly Fishes

Mollies are a tropical fish of the genus Poecilia. With over 30 species belonging to this genus it's easy to be confused when trying to distinguish mollies from one another. There are some basic molly types that can be recognized in your local pet shop and then there are still others that only fish specialists will recognize or be familiar with. Interestingly, mollies are related to platies and guppies, which also belong to the same genus.

  1. Short-Finned Molly

    • The short-finned molly is one of the major groups that wild-caught mollies fall into, the other being the sailfin. The short-finned molly, Poecilia sphenops, is best represented by the black molly, familiar to aquarium enthusiasts. It is also known as the common molly, and like other live bearers in the genus Poecilia, it's a freshwater fish, but benefits from a little aquarium salt to simulate brackish water conditions. The species is distributed through Central and South America, Mexico and Colombia.

    Sailfin Mollies

    • The sailfin molly, Poecilia latipinna, is distinguished by its large dorsal fin. In the wild it is often found in tidal ditches and semi-saltwater canals from North Carolina to Mexico. This is a different sailfin molly from the Mexican sailfin molly, Poecilia velifera, which grows much larger than the sailfin molly. The Mexican sailfin, also known as the "Giant Sailfin," also sports a much more dramatic dorsal fin, with closer to 18 rays compared to the sailfin's 14.

    Hybrid or Fancy Mollies

    • Breeding short-finned mollies with sailfin mollies has produced a number of variations. Black hybrids between sailfins and short-finned mollies are known as "midnight mollies." Other variations such as lyretails, have fancy, elongated caudal (tail) fins in the shape of a lyre. Dalmatian mollies have black and white mottled coloring over their bodies. The platinum lyretail is yet another hybrid variation of the giant sailfin, with a striking silver color and large lyre-shaped caudal fin.

    Balloon Molly

    • Another variation of the sailfin molly, (P. latipinna), the balloon molly, has a humped back and an extended, round belly which makes the fish resemble a balloon. These fish can also exhibit a large dorsal fin as well as a lyre tail. Balloon mollies can be kept in a fresh or saltwater aquarium due to their preference for brackish water. Some fish enthusiasts consider balloon mollies deformed, because their humped backbones distinguish them from other mollies, which they were bred to be distinct from.