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     According to the U.S. Environmental Protection Agency's standard (daily intake not higher than 0.1µg/kg ), taking a 50 kg person as an example, the daily intake should not be higher than 5 micrograms. Assuming this 50 kg person eats fish every day, then:
    Fish containing no more than 50 micrograms of methylmercury per kilogram can be eaten up to 100 grams.
    Fish containing no more than 100 micrograms of methylmercury per kilogram can be eaten up to 50 grams.
    Fish containing no more than 200 micrograms of methylmercury per kilogram can be eaten up to 25 grams.
    Fish containing no more than 500 micrograms of methylmercury per kilogram can be eaten up to 10 grams.
    Fish containing more than 500 micrograms of methylmercury per kilogram had better not be eaten.

    According to different weights of consumers and different methylmercury content of various fish, I made a seafood consumption calculator.

     In addition, I suggest that people who are exposed to high-methylmercury environment eat more lean meat, pumpkin, onion, garlic, and other food with high selenium content to reduce the harm of methylmercury to the body.

     The generally higher methylmercury level of tuna is due to its long growth cycle (5 to 35 years) and large body size (90 kg to 300 kg). Large fish like tuna are at the top of the food chain in marine ecosystem. Since substances in the food chain accumulate in every trophic level, more toxins accumulate in consumers at the top.


     Although a lot of advertisements say that tuna has high nutritional value, the level of methylmercury in tuna is too high. We can choose salmon instead of tuna. Salmon has high nutritional value and low methylmercury content.


     Although the methylmercury level of canned light tuna is lower than that of other tuna, it is not encouraged to eat more light tuna because it is difficult for consumers to distinguish different types of tuna. For pregnant women, the elderly, and children, it is best not to eat tuna.

Table of Methylmercury Level in Tuna

Date Source: U.S. EPA&FDA

Image by Jordan Whitfield

Advice on Tuna

Image by Connie Perez

Advice on Grouper and
Freshwater Fish

     Grouper, a commonly eaten fish, cannot be eaten too much. Because the grouper has a long life span, ranging from 20 to 50 years, the toxins in the body accumulate over time. Secondly, groupers are large(11 kg to 180 kg) and at the upper level of the food chain, and thus accumulate more toxins. For pregnant women, young children, and the elderly, the consumption should be appropriately reduced.


     Although marine fish are more susceptible to methylmercury pollution, freshwater fish may be polluted by other industries or water. Therefore, there is no need to stop eating marine fish. The choice of marine fish or freshwater fish mainly depends on whether the area where this fish lives is polluted, and the degree of pollution. We should try our best to eat moderately and diversifiedly.

Image by Pesce Huang

Seafood Recipes

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