Ratio mercury / selenium in fish
NB: Graph on the link beneath.
Ratio Mercure / Sélénium dans la sardine, le maquereau et le thon
https://mirzoune-ciboulette.forumactif.org/t1264-poisson-frais-et-huile-composition#14421
We should have less Hg (mercury) than Se. Maximum ratio 1.
I’d avoid fish predator as Haddock, sea bream, halibut and specifically tuna. Never more than once a week when eating a predator.
Tuna ratio is 331/36. It depends on the species too. Therefore, it's highly toxic. Expressed in ppm per 100g of fish, this gives a ratio of 9.2. But in canned fish, this ratio is closer to 2/1 or 1/1 (extracted oil), I think.
Source: Calypso, 2016 (équipe Cousteau)
Search Google with: Mercure et étude calypso 2016.
Analyze (in French)
https://auculdubateau.wordpress.com/2016/06/02/le-poisson-est-il-pollue-voici-les-faits-espece-par-espece/
Table
Same, but drop down the menu on the link and bring back the table, which you will divide into 2, for easier reading.
Highlight:
Canned tuna contains much less fat than fresh tuna (used for other purposes, such as omega-3s). There's not really a problem because mercury is mainly found in the fat. (This tuna is therefore acceptable once a week, except for pregnant women and children, contrary to what you might usually read.) Obviously, we'll favor the least polluted sources...
Please keep an eye on Se and Mg (antagonists of mercury)!
Additional info
See too for comment (scroll downwards to see different sources):
Ratio Mercure / Sélénium dans la sardine, le maquereau et le thon
https://mirzoune-ciboulette.forumactif.org/t1264-poisson-frais-et-huile-composition#14421