Although the species is relatively drab for the majority of the year, breeding males are brilliant. They are deep blue dorsally, and have blue median fins with light blue spots and yellow-orange margins. Some males develop orange-red anal fins with red spots; paired fins are also yellow-orange with red spots on the pectoral fin. Fresh and brackish waters from northeastern Florida to Key West and northern Gulf of Mexico to Cuba. Primarily estuarine, the killifishes (Cyprinodontidae) are inshore fishes associated with a variety of low-salinity habitats (including marshes, seagrass beds, oyster, etc.). However, most killifish species have wide salinity tolerances, and can sometimes be found in habitats ranging from hypersaline tidal pools to freshwater reaches. The Gulf killifish is no exception, and can tolerate wide variances in salinity.
Citation information: U.S. Geological Survey. . Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [11/10/2015].