The geographic scope of species introductions has increased dramatically in the last 200 years. One of the greatest challenges to understanding the ecological consequences of non-native species is that it has been difficult to identify the attributes that allow them to become established outside their native range. This challenge is compounded by anthropogenic habitat alteration that often enhances the establishment and expansion of non-native species. Fishes in the family Cichlidae are notoriously adaptive, and contribute more non-native species to North America than any other fish family. This is especially true in Florida (USA), where 18 cichlid species have become established. The Mayan cichlid (Cichlasoma urophthalmus) was first documented in south Florida in 1983, and is present in many freshwater and estuarine habitats. This study reports a northward range expansion by C. urophthalmus, demonstrates the connectivity between altered freshwater habitats and tidal estuarine habitats, and suggests that the estuarine populations are ephemeral and dependent upon colonisation from populations in altered freshwater habitats.