Poecilia vandepolli, or Van de Poll's molly, is a poeciliid fish native to the ABC islands of the Lesser Antilles, namely Aruba, Bonaire, and Curaçao.

It is a euryhaline species and one of the most common fish in its range, inhabiting fresh, brackish, salt, and hypersaline waters.

The saltwater specimens grow faster and become more robust and more colorful, but the species is drawn to the freshwater habitats which disappear in each dry season and must be recolonized when the rains return.

sphenops P. kykesis P. latipinna Based on the similarities between the two species noted by Hubbs, Poeser considered P. vandepolli to have common ancestry with P. vivipara from South America.

Its ancestral form diverged approximately 150,000 years ago when the sea levels were lower and the Lesser Antilles islands, which the species inhabits today, were connected to mainland Venezuela.

The connection likely enabled the most recent common ancestor of P. vandepolli and P. wandae to populate the area, while the subsequent sea level rise led to the emergence of two distinct species.

The specimens living in marine habitats have larger bodies, longer dorsal fins, and stronger coloration.

[3] P. vandepolli is one of the most common fish species in the coastal habitats across the Lesser Antilles and is found in nearly all freshwater localities.

[1] It is one of only five native species inhabiting the fresh waters of Aruba, the others including the American eel (Anguilla rostrata) and the mountain mullet (Dajaus monticola), and is by far the most abundant and dominant along with the invasive Mozambique tilapia (Oreochromis mossambicus).

The sole exception are the hypersaline environments, where salinity levels change through evaporation and rainfall, the latter also occasionally leading temperatures to rise far above 36°C, which is lethal to fish.

[4] Once the torrential rain flooding commences, the chemical cue from the surface runoff laden with terrestrial organic compounds attracts the mollies from the sea to colonize the reemergent freshwater systems, where they reproduce quickly.

[3] The pupfish Cyprinodon dearborni, which can also live in all salinities, shares the molly's dietary habits and is a major competitor.

[4][3] In confined water bodies population density is limited by the availability of food: most offspring starve or fall prey to adults.

Freshwater and supersaline habitats are generally free of predators, but on Curaçao birds and trematodes prey on the mollies.

[4] An observation of hundreds of mollies in a stream on Aruba revealed large males chasing females "incessantly".

[3] The ability to intensify its orange coloration after a high-carotenoid diet and the existence of highly-blotched specimens might qualify P. vandepolli for ornamental fish trade.