Watersnakes serve a variety of important roles in aquatic ecosystems with many species being of conservation interest. The northern water- snake (Nerodia sipedon) has some populations of concern, but is found in a wide variety of aquatic habitats throughout North America. Although previous studies have examined the diet of this typically piscivorous species, research has not addressed whether the northern watersnake is preferentially selecting particular fish as prey. In this study, we sampled snake stomach contents and used Chesson's alpha selection index (αi) to investigate whether northern watersnakes are eating fish families in proportion to their availability or are preferentially selecting or avoiding specific fish families. At the Sloughs Wildlife Management Area in western Kentucky, the northern watersnake fed on fish from six families in 2013 (n = 15) and 2014 (n = 36). Five of those fish families were eaten in proportion to their availability but avoided pirate perch (Aphredoderus sayanus), the lone member of the family Aphredoderidae. This is the first study testing prey preferences in the northern watersnake.