Estimating body size of fishes from remains recovered from piscivores, archaeological sites, and sedimentary deposits is desirable but rarely accomplished because the relationships between the size of a fish and its durable anatomical structures are largely unknown. Regression equations to predict the size or weight of 41 common Hawaiian reef fishes from sagittae (saccular otoliths) are presented. Data are also grouped into higher taxa to permit size predictions when otoliths cannot be assigned to species.