Mercury (Hg) enters the environment through natural processes and human activities. There are three forms of Hg: elemental (metallic) mercury, inorganic mercury salts and organic mercury compounds. Methylmercury (MeHg) is often formed from inorganic mercury during biological processes such as methylation by microorganisms in water and sediment. MeHg can accumulate in aquatic organisms including fish. People are exposed to very low levels of mercury in the air, water and food. Some people may be exposed to relatively higher levels of mercury by eating MeHg-containing fish. MeHg accumulates in the human body over time and because it is a known neurotoxin, it is necessary to limit human exposure to MeHg. To protect public health, Health Canada has proposed mercury guidelines and advisories for fish consumption based on total mercury (THg; all forms of Hg in a sample). This dataset was collected as part of long-term monitoring of mercury levels in various species of fish in Albertan water bodies (e.g., rivers and lakes). Fish were collected by Alberta Environment and Parks, and the chemical analyses and data quality assurance and control were conducted by Alberta Health. This dataset forms the basis for part of the series of Alberta Health Mercury in Fish reports (found here: http://aephin.dha.io/pdfs/navPages/Environmental_Public_Health_Science_Publications.pdf ) and is also used to inform or issue local fish consumption advisories on My Wild Alberta website: https://mywildalberta.ca/fishing/advisories-corrections-closures/fish-consumption-advisory.aspx Each row in the dataset represents the concentration of THg in a single fish sample for a given species, at a specific location during a particular year. This dataset contains data from 1997 to 2023. The dataset is useful for the general public, specifically for people who rely on local fish for subsistence or recreational anglers. This dataset may also be useful to academic researchers studying Hg in the environment.