Fishes exhibit an extraordinary degree of variation in ontogenetic strategies among and even within species, often associated with tradeoffs between foraging and predation risk that have important consequences for overall growth, survival, and eventual reproduction. Fish eye lenses are nitrogen rich and develop in successive layers which are metabolically inactive after forming, making them useful in elucidating the ontogenetic trajectory of fishes through carbon (δ13C) and nitrogen (δ15N) stable isotope analyses (SIA). We are using successive-layer eye lens SIA to understand the trophic ontogeny of Arctic Charr (Salvelinus alpinus) and Brook Trout (Salvelinus fontinalis) in Maine lakes. Maine represents the southern extent of the North American native range of Arctic Charr, which show drastic variability in adult trophic niche relative to the typically piscivorous and more warm-water tolerant Brook Trout. Individual eye lens layers from 16 fish across 4 lakes were run for δ13C and δ15N SIA. We found evidence of considerable variation in the ontogenetic trajectory of Arctic Charr across lakes. δ13C values revealed apparent benthic-pelagic resource dependence shifts in one population, while others appeared to consistently depend on pelagic resources. δ15N values show evidence of a transition from planktivory to apex piscivory in one lake, and a lifetime as a low order consumer in another. Variation in ontogeny may be a product of lake-specific habitat and community structure. For instance, we found evidence that temperature and oxygen trends may contribute to benthic-pelagic shifts, and lifetime pelagic dependence could help arctic charr avoid intense fish competition or predation in the littoral zone of more diverse lakes. Identifying variable ontogeny, and understanding environmental factors that may drive it, may be useful in building long-term management goals for Arctic Charr, particularly in southern-edge populations experiencing rapid change.