4. Herring (2,150 mg per serving)
Herring is a medium-sized oily fish. It is often cold-smoked, pickled, or precooked and sold as a canned snack.
Smoked herring is a popular breakfast food in countries such as England, where it’s called kippers and served with eggs.
A 3.5-oz (100-g) serving of herring contains almost 100% of the DV for selenium and 779% of the DV for vitamin B12.
Omega-3 content: 2,150 mg of EPA and DHA (combined) in 3.5 oz (100 g)