Growth rates of juvenile (1–8 g) Sacramento blackfish, an omnivorous California cyprinid which grows to >1.5 kg, were measured at three temperature ranges in laboratory aquaria where several diets were offeredad lib. and at four stocking densities in small ponds where natural food was available. Growth rates generally increased with elevations in environmental temperature. Growth in aquaria was possible with strictly plant-based diets, but was faster with pelleted diets higher in protein, lipids, and total calories. Growth rates in ponds increased with decreased stocking densities and approximated or exceeded those measured in laboratory aquaria for blackfish fed pelleted diets. The data also support the importance of energy-rich food organisms (e.g., zooplankton) in the diet of young-of-the-year blackfish in Clear Lake, California.