The elongate body plan is present in many groups of fishes, and this morphology dictates functional consequences seen in swimming behavior. Previous work has shown that increasing the number of vertebrae in artificial systems increases stiffness and mean swimming speed. This demonstrates the impacts of morphology on both material properties and kinematics, establishing mechanisms for form contributing to function. However, we wanted to investigate relationships between form and ecological function, which manifested as differences in dietary strategies between fish species. This study aims to characterize and compare the kinematics, material properties, and morphology of four species of elongate fishes: Anoplarchus insignis, Anoplarchus purpurescens, Xiphister atropurpureus, and Xiphister mucosus. We hypothesized that the combination of these properties could distinguish the species from each other. To calculate kinematic variables, we filmed these fishes swimming of their own volition. We also measured body stiffness by bending sacrificed individuals in different stages of dissection (whole body, removed skin, removed muscle). Finally, we counted the number of vertebrae from CT scans of each species to quantify vertebral morphology. The results from the principal components analysis suggested that the elongate fish species can be distinguished from one another by their material properties, morphology, and swimming kinematics. With this information combined, we were able to draw connections between the physical properties of the fishes and their dietary ecologies since the only herbivore, X. mucosus, was dramatically separated from the other species.