Plains Topminnow (Fundulus sciadicus) populations have experienced large declines throughout the Central Great Plains, with Western Mosquitofish (Gambusia affinis) introductions suggested as a contributing factor. There are limited studies identifying the food habits of Plains Topminnow and the trophic interactions with Western Mosquitofish. This study sought to determine if a diet overlap exists between the Plains Topminnow and the introduced Western Mosquitofish by identifying the feeding habits of both species. We analyzed diets from lentic and lotic populations of Plains Topminnow captured in August and found lentic topminnows employed a generalist diet while lotic topminnow selected for gastropods. Additionally, Western Mosquitofish diets from regionally proximate lotic and lentic populations also displayed a generalist diet consisting of benthic, littoral and terrestrial macroinvertebrates. The two species did not show overlapping diets based on Schoener’s Index. Therefore we suggest the introduced Western Mosquitofish do not likely impact Plains Topminnow populations through food resource competition
