Also known as the Dwarf Livebearer, Least Killifish are one of the smallest species of freshwater fish in the world and they are the smallest species found in North America. These fish are native to the south-eastern United States where they can be found in shallow, densely-vegetated and slow-moving waters. They may even be found in brackish conditions. The Least Killifish can be identified by their olive coloration and the dark stripe running laterally along the body. Most specimens also exhibit a dark spot on the dorsal fin and females of the species may also have a spot on the anal fin.