In the catchment of the Lerderderg River, Victoria, Australia, gold-mining operations using the mercury amalgation process were carried out until 50 years ago. The distribution of mercury in water, sediments and fish from the Lerderderg River has been investigated. Mercury in water values were low (0·01 to 0·31 μg litre −1) and showed no clear correlation with sites of sampling. However, mercury concentrations up to 130 μg g −1 in sediments revealed a pattern of mercury contamination which could be related to past gold-mining activities. Elevated mercury levels were not found in brown trout Salmo trutta, but in river blackfish Gadopsis marmoratus, concentrations elevated to as much as 0·64 μg g −1 were found in fish living at sites elevated mercury sediment levels.