Fish is rich in nutrients and perfectly integrates a balanced diet. However, whether it is wild or farmed fish, these animals ingest substances that can be harmful to human health. How to find the right balance? How Much Fish Can I Eat?

Fish is rich in vitamins (A, D, B3, and B12), minerals, and trace elements (iron, zinc, iodine, and selenium). It can therefore obviously be considered a healthy food in terms of nutritional values. Crustaceans and mollusks are nutritionally comparable. Oily fish such as herring, mackerel, tuna, sardines, and salmon also contain a lot of omega-3, which protects in particular against cardiovascular diseases.

But unfortunately, in the wild, these animals do not live in pure water. They swim and feed in seas and oceans polluted with nanoparticles of waste and heavy metals like mercury. Oily fish, in particular, store heavy metals and dioxins in their fat, and these substances end up in our bodies through our food.

The amount of mercury ingested by a fish depends mainly on its diet. Fish that eat a lot of plankton, such as herring, salmon, squid, and trout, contain less mercury (less than 50 micrograms per kg) than predatory fish and crustaceans like lobster, mackerel, or tuna ( 290 micrograms per kg). Swordfish, a delicious white fish often on the menu in the Mediterranean regions, is the leader, with no less than 1212 micrograms per kg!

An overdose of mercury can lead to poisoning in humans (Minamata syndrome). Symptoms are disturbances in balance and coordination of movements (ataxia), numbness in the hands and feet, and general muscle weakness. But to run this risk, you have to eat a lot, a lot of fish or shellfish.

In 2015, the European Food Safety Authority (EFSA) conducted a study on the mercury content of a number of foods. She concludes that a weekly intake of 1.3 micrograms of mercury per kg of body weight is the maximum acceptable dose for adults. For a 60 kg person, this is 78 micrograms, for a 75 kg person the limit is 97.5 micrograms.

How much fish you can eat is therefore a question that must be answered in a very nuanced way. It depends on the type of fish, but there is also an important ecological aspect to consider. Overfishing is very damaging to the environment and disrupts biodiversity. It is therefore ideal to turn to fish and shellfish labeled ASC or MSC, which are guaranteed to come from sustainable fishing.

Is farmed fish better than saltwater fish? The answer is no. Often antibiotics and pesticides are used and the diet served to farmed fish consists mainly of fishmeal made from marine fish.

The FDA recommends consuming 2-3 servings of lower-mercury fish per week, or 8 to 12 ounces. It is useful to vary the species and bet on seasonal arrivals. Fresh fish will be preferred, canned fish is a very good option (check the salt content though), while fried fish should be kept to a minimum.

Betsy Wilson

A true science nerd and pediatric nursing specialist, Betsy is passionate about all things pregnancy and baby-related. She contributes her expertise to the Scientific Origin.