Lythrurus fasciolaris (Scarlet Shiner) and Lythrurus umbratilis (Redfin Shiner) are closely related minnow species usually exhibiting a parapatric distribution in the Ohio River basin; however, areas of sympatry do exist and hybridization has been documented. In Eagle Creek (Kentucky River drainage), a stream capture event is likely responsible for creating the contact zone, providing a unique opportunity to study hybridization. In this paper, we conduct a morphological analysis of nuptial males from six Lythrurus populations in Eagle Creek. Our results show longitudinal variation in morphology. Individuals from downstream areas exhibit a novel phenotype with a robust body and low meristic counts. In contrast, upstream areas contain individuals resembling Redfin Shiner. Overall, 62% of individuals examined in Eagle Creek have the novel phenotype and 27% have the Redfin Shiner phenotype. Local selection pressures and apparent geographical isolation may be fostering the development of a distinct phenotype via introgressive hybridization.