A clear characteristic for the rainbow trout is the fairly wide longitudinal line on the gill covers and on the sides. This salmonoid fish that originates in North America has been planted in Finland several times. However, rainbow trout does not breed very easily in Finnish waters, and therefore the rainbow trout populations in natural waters depend upon plantings. Rainbow trout is, however, well suited for fish farming in ponds and net basins. The downside of fish farming is often eutrophication of the nearby waters. Rainbow trout is a delicious and popular food fish, even though it is often called the broiler of Finnish waters. Counted in production value, the rainbow trout is the most significant fish in Finland. The rainbow trout reaches the age of only eight years.