Longer and more intense thermal stratification, coupled with widespread browning, is expected to reduce summer oxythermal refugia for brook trout (Salvelinus fontinalis) in small lakes; however, the influence of these climate-driven changes on brook trout diet remains unclear. The Adirondack region (New York, USA) provides a model system to study brook trout ecology given the high density of remote trout ponds. Although considered generalists, it is known that lentic Adirondack brook trout exhibit seasonal temporal variations in individual specialization between lakes. Following optimal foraging theory, brook trout are expected to use previously underutilized resources as competition for space increases. Therefore, we hypothesize that increased intraspecific competition resulting from decreased oxythermal habitat and access to littoral resources will expand niche width and increase individual diet specialization of brook trout in the summer compared to the spring and fall. We studied brook trout diet and body condition (Fulton’s K) across seasons in five small, remote Adirondack lakes of varying depth and dissolved organic carbon concentrations. Stomach content analysis and stable isotope analysis of δ13C and δ15N (sampled via gastric lavage and fin clips, respectively) were used to infer short- and long-term brook trout diet in relation to seasonal habitat availability. High-frequency temperature and oxygen loggers and sonde profiles tracked changes in suitable oxythermal habitat from May to October 2024, allowing us to estimate seasonal volume of oxythermal habitat suitable for brook trout. We observed seasonal diet switches from benthic to pelagic resources along with decreased surface feeding behavior when water temperatures exceeded the suitable threshold (20℃). Preliminary results suggest significant differences in body condition across some but not all sites. We hope that the results of this study will help inform management decisions such as optimal stocking numbers and recreational angling regulations in these changing and valued environments.