[narutouzumaki]

Does that mean that tuna does not have much selenium? Would it be possible to mitigate the effects of a tuna rich diet with by also eating other food rich in selenium?

[stagbeetle]

I don't have the ratio for tuna off-hand, but IIRC a selenium supplement is all you need to counteract a fish-heavy diet.

But, yes. You can also supplement fish with higher sel:merc ratios to balance it out.

[nibstwo]

Tuna is a big fish. The smaller the fish, the higher the ratio of selenium to mercury. Tuna is the cut off, size wise.