This study is concerned with the age and growth of perch (Perca fluviatilis L.) in two contrasting Scottish lochs‐the Dubh Lochan and Loch Lomond. Age and back‐calculated growth were determined from annual rings in the opercular bones, and during the 2‐year project 470 perch from the Dubh Lochan and 796 from Loch Lomond were examined. Growth in length in the two lochs, though similar for the first 2 years, differed thereafter, the average length at 8 years in the Dubh Lochan being less than 15 cm, that in Loch Lomond more than 23 cm at the same age. In neither locality did the growth of perch follow the Von Bertalanffy growth formula. Reasons for differential growth rates are discussed and comparisons made with the growth of perch in other waters in Europe and North Am