Mercury is a toxic metal that can cause serious health problems, including neurological damage, developmental disorders, and kidney problems. It is found in the environment from natural sources, such as volcanic eruptions, and from human activities, such as mining and burning fossil fuels.

Mercury can enter the food chain through the water, where it is absorbed by fish and other aquatic organisms. When humans eat fish that have been contaminated with mercury, they can also become contaminated.

A new study by researchers at the University of Washington has found that the amount of mercury in fish can vary depending on the type of fish, the size of the fish, and the location where the fish was caught.

The study found that larger fish tend to have higher levels of mercury than smaller fish. This is because larger fish eat smaller fish, and the mercury accumulates in their bodies.

The study also found that fish caught in polluted waters tend to have higher levels of mercury than fish caught in clean waters. This is because mercury can enter the water from industrial sources, such as factories and power plants.

The researchers said that their findings could help people make healthier choices about the fish they eat.

"By choosing smaller fish and fish caught in clean waters, people can reduce their exposure to mercury," said lead researcher Dr. Emily Sunderland.

The study was published in the journal Environmental Science & Technology.

Here are some tips for reducing your exposure to mercury:

* Choose smaller fish, such as sardines, tilapia, and trout.

* Avoid eating large predatory fish, such as tuna, shark, and swordfish.

* Eat fish that are caught in clean waters.

* Limit your intake of fish to no more than two servings per week.

* Pregnant women and children should avoid eating fish that are high in mercury.