Rainbow Trout

(Onchorynchus mykiss)
Image of rainbow trout.
Image of rainbow trout.

© CSIRO Marine Research 1999. Used with permission.
Rainbow trout are cold-water fish. They are a popular fish for farming in Australia and throughout the world. Trout farming is not a high revenue earner, but the low risk involved makes it an attractive species to farm.

Rainbow trout can grow up to 90 cm and 14 kg, though they are usually harvested when they are about 30 - 45 cm and 0.5 - 1 kg. The rainbow trout has a slight reddish or pinkish stripe along the midline of its body. It also has black spots on the body and prominent spots that radiate outwards on its tail. Other main identifying features include:
  • a large jaw that extends past the eye level
  • the presence of an adipose fin
  • the pectoral fins are positioned low on the side
  • the pelvic fin is located well behind the pectoral fins.

Rainbow trout are found in both fresh water and salt water. They are native to streams, rivers and lakes that drain into the eastern Pacific Ocean. Rainbow trout in Australia are found in the wild, swimming in lakes and streams with a moderate to fast flow. They are commonly farmed in cooler regions of Australia, such as the south-west and south-east, and in Tasmania.
Map of Australia showing rainbow trout habitat
Map of Australia showing rainbow trout habitat


Water quality factor
Optimum range
16 - 18°C
6.5 - 9
Dissolved oxygen
More than 5 mg/l
30 - 100 cm
20 - 200 mg/l
50 - 100 mg/l
Less than 0.02 mg/l
Less than 0.1 mg/l
0 - 35 ppt