I’m seeing conflicting sources online. Some say they’re very low, such as Cod having 10mg per 100g, others say 3500mg per 100g. Same with salmon, same with mackerel. I would like a definitive answer.
Definitely not 10mg.
USDA database has full info on all 3.
https://fdc.nal.usda.gov/fdc-app.html#/food-details/173686/nutrients
https://fdc.nal.usda.gov/fdc-app.html#/food-details/175119/nutrients
https://fdc.nal.usda.gov/fdc-app.html#/food-details/171955/nutrients