Poecilia sphenops is a species of fish, of the genus Poecilia, known under the common name molly; to distinguish it from its congeners, it is sometimes called short-finned molly or common molly. They inhabit fresh water streams and coastal brackish and marine waters from Mexico to Colombia.

 Molly fish are a staple of freshwater fishkeeping, and have been popular among aquarists for quite a while!