Sardines seem to have the lowest mercury concentration of any fish: https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1

Sardines seem to have the lowest mercury concentration of any fish: https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1990-2012 https://www.fda.gov/food/metals-and-your-food/mercury-levels...