The golden trout ( Truite dorée - French) or California golden trout (Oncorhynchus mykiss aguabonita) is a sub-species of the rainbow trout native to California. It closely resembles the juvenile rainbow trout. The golden trout is native to Golden Trout Creek (tributary to the Kern River, Volcano Creek (tributary to Golden Trout Creek), and the South Fork Kern River. A sibling subspecies, Little Kern golden trout (O. m. whitei), was historically found only in the Little Kern River but is now found in other nearby creeks, as well. Another sibling subspecies, Kern golden trout or Kern River rainbow trout (O. m. gilberti), was once widely distributed in the Kern River system, but was reduced to a limited section until transplantation to other creeks. The golden trout was designated the state fish of California in 1947.
The golden trout has golden flanks with red, horizontal bands along the lateral lines on each side and about 10 dark, vertical, oval marks (called "parr marks") on each side. Dorsal, lateral and anal fins have white leading edges. In their native habitat, adults range from 6–12 in (15–30 cm) long. Fish over 10 in (25 cm) are considered large. Golden trout that have been transplanted to lakes have been recorded up to 11 lb (5 kg) in weight.
The golden trout should be distinguished from the similarly named golden rainbow trout, also known as the palomino trout. The golden rainbow is a color variant of the rainbow trout.
The golden trout is commonly found at elevations from 6,890 feet (2,100 m) to 10,000 feet (3,000 m) above sea level, and is native only to California's southern Sierra Nevada mountains. Preferred water temperature is 58–62 °F (14–17 °C) but they can tolerate temperatures in degraded streams on the Kern Plateau as high as 70 °F (21 °C) so long as those waters cool during the night. The only other species of fish indigenous to the native range of California golden trout is the Sacramento sucker (Catostomus occidentalis occidentalis).