Environmental temperature has a major impact on ontogeny of early development in teleost fish because of differential effects on rates of growth, cellular differentiation, and metabolism. Environmental temperature can thus lead to changes in relative rates of the development of physiological and anatomical components of the body including bone formation. Changes in ontogeny or rate of skeletogenesis can lead to variations in morphological or physiological phenotypes and may affect the relationship of form and function for foraging and predator avoidance. This study examined the normal ontogeny of skeleton in yellow perch, assessing development of the axial skeleton, the cranio-facial region, and the fins, in yellow perch larvae and pre-juveniles. The ontogeny of skeletogenesis in yellow perch was comparable to other related species. Fish were also reared at constant temperatures of 12, 15, or 18 °C to examine the influence of developmental temperature
post-hatch fish were moved to a common 18 °C. Warm incubation temperatures (15 and 18 °C) increased the extent of ossification for some bones in all body regions, particularly in the exogenous feeding, and the pre-juvenile fish (30 and 40 days post hatch). This was evident in both the extent of ossification and counts of meristic characters of ossified bones. Significantly lower ossification and meristic counts in 40 dph fish reared at 12 °C may limit jaw functionality and suggests an undeveloped vertebral column and fins. Future studies should investigate swim performance and foraging to determine if delayed bone development has potential fitness costs.