Mercury in fish: the low-mercury, high-omega-3 short list

Mercury (ppm) by species against omega-3 yield, using FDA and EPA data. The fish that maximize EPA+DHA per serving while staying under the weekly mercury limit, and the ones to limit.

1. 01

   Wild salmon (canned or fresh)

   ~0.022 ppm mercury (FDA), among the lowest of any commonly eaten fish, paired with ~1.5-2 g EPA+DHA per 100 g cooked. The best mercury-to-omega-3 ratio on the list: high oily-fish omega-3 yield with negligible mercury. Canned wild salmon adds soft, edible bones (calcium). The default pick for hitting omega-3 targets from food rather than a fish-oil capsule.

2. 02

   Sardines

   ~0.013 ppm mercury (FDA), about the lowest measured, with ~1.4 g EPA+DHA per 100 g. Short-lived, low on the food chain, so they accumulate little mercury. Canned in water or olive oil, shelf-stable, and among the cheapest omega-3 sources per gram. The constraint is palatability, not safety.

3. 03

   Atlantic mackerel (not king mackerel)

   ~0.05 ppm mercury for Atlantic/Pacific mackerel, with one of the highest omega-3 yields of any fish (~2.5 g EPA+DHA per 100 g). Critical distinction: Atlantic mackerel is a low-mercury best choice, while KING mackerel is on the FDA avoid list at ~0.73 ppm. The species name matters more than the category.

4. 04

   Canned light tuna (skipjack)

   ~0.13 ppm mercury (FDA), a 'best choice' in moderation, with ~0.27 g EPA+DHA per 100 g. The cheapest reliable shelf-stable protein-plus-omega-3 source. Skipjack (light) runs roughly 3x lower mercury than albacore (white) tuna, which is the single most useful swap most people can make at the can shelf.

5. 05

   Albacore (white) tuna

   ~0.35 ppm mercury (FDA), roughly 3x canned light tuna. A 'good choice' the FDA caps at about one serving per week for adults, and lower for pregnancy and children. Higher omega-3 than skipjack, but the mercury limit makes it a once-weekly item, not a daily protein. When in doubt at the shelf, light tuna is the higher-frequency choice.

6. 06

   Shrimp, cod, tilapia, pollock

   All under ~0.04 ppm mercury (FDA best choices) and safe to eat several times a week, but low omega-3 (under ~0.3 g EPA+DHA per 100 g). These are excellent low-mercury lean proteins; they just do not move the omega-3 needle. Eat them for protein and variety, and get EPA+DHA from salmon, sardines, or mackerel.

7. 07

   Avoid list: king mackerel, shark, swordfish, tilefish, bigeye tuna, marlin

   ~0.7-1.5 ppm mercury (FDA avoid list), the large, long-lived predators at the top of the food chain that concentrate the most methylmercury. The FDA and EPA advise avoiding these entirely for anyone pregnant, breastfeeding, or feeding young children, and limiting them for everyone else. No omega-3 benefit justifies these mercury levels when salmon and sardines exist.