The order Cyprinodontiformes contains a wide variety of ray-finned fish, such as killifish, many of which have been shown to be able to tolerate a wide range of environmental conditions including temperature and salinity. In fact, many of the species within this order have been shown to exhibit terrestrial locomotion. Some species are able to sustain life on land for several months at a time. Others will spend only small portions of their lives on land due to environmental stressors, escaping predators, poor water conditions, etc. Many species are suspected of exhibiting amphibious behavior due to shallow water depths and tidal fluctuations, yet this has often been subject to contention. The exact number of species which exhibit amphibious traits is also up for debate; however, the present study seeks to examine the current background literature on each species within the order Cyprinodontiformes and assign a degree of amphibious-like behavior to each species. Analysis was performed with confirmed and suspected amphibious species based on life history data. Based on this analysis, an ancestral state reconstruction using BayesTraits was conducted to determine the likelihood of amphibiousness in a common ancestor. Phylogenetic analysis and visualization was conducted using FigTree. Preliminary results suggest ~87% likelihood the common ancestor of Fundulidae was non-amphibious, though this figure lowers drastically to 50% when our suspected amphibious species are included in the analysis. Additional data is currently being collected to continue reconstructing amphibious behavior throughout order Cyprinodontiformes.