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Mercury in fish

(Last reviewed December 2020)

Fish is an excellent source of protein, essential omega-3 fatty acids, iodine, important vitamins and is low in saturated fat. Although mercury is present at low levels in most fish, there is no need for anyone (including pregnant and breastfeeding women) to stop eating fish altogether.

Mercury occurs naturally in the environment and builds up in fish over time. All fish contain some mercury with most fish having low levels. Only a few species have higher amounts. The amount of mercury depends on the age of a fish, the environment in which it lives and what it eats. Big fish that have long lifespans and predatory fish such as swordfish and shark/flake tend to have higher levels of mercury than other smaller, younger fish.

Most people only eat moderate amounts of fish so the benefits of eating fish far outweigh any potential risks related to mercury intake.

Eating fish when pregnant

High levels of mercury can damage the nervous system in the human body. Some studies report a link between high consumption of fish by pregnant women and subtle developmental delays in their children.

If you are intending to become pregnant or are pregnant, it's important to know how much fish (and what type) you can safely eat. Unborn babies, infants and young children are especially vulnerable to excessive mercury intake, as they are going through rapid growth and development.

How much fish should I eat?

The below provides guidance on the size and number of portions that can safely be consumed in Australia for different types of fish and population groups. If you live in New Zealand consult www.mpi.govt.nz.

Women who are pregnant or planning pregnancy: 1 portion is 150 grams#

Children (up to 6 years): 1 portion is 75 grams#

  • 1 portion per week of Orange Roughy (Deep Sea Perch) or Catfish and no other fish that week, OR
  • 1 portion per fortnight of Shark (Flake) or Billfish (Swordfish/Broadbill and Marlin) and no other fish that fortnight

Rest of the population: 1 portion is 150 grams#

  • 1 portion per week of Shark (Flake) or Billfish (Swordfish/Broadbill and Marlin) and no other fish that week

#To avoid exceeding the portion sizes above over the given time periods in the table, you should:

  • Check the serving size on the label of packaged or canned fish. One serving could be higher or lower than the portion sizes in the table.
  • Divide the portion size into smaller amounts, for example, by having two amounts over two meals or three even smaller amounts over three meals.

If you are in doubt about the type or name of the fish you want to order, ask the sales person or service staff.

Note: The advice above provides guidance on fish consumption in portion sizes. These portion sizes are different to the suggested serving size of 100 g for fish noted in the Australian Dietary Guidelines.

More information

Note: While we have updated the design and references and refined content in the Mercury in Fish brochure, the recommended size and number of portions of fish that can safely be consumed has not changed since our earlier advice in 2011.

The recommended 2-3 serves of fish/seafood per week has been removed from the table providing guidance on the size and number of portions that can safely be consumed as this reflects advice in the Australian dietary guidelines rather than guidance for safe consumption. 

Additionally, reference to serving sizes in the table have been updated to 'portions', to differentiate from dietary guidelines which refer to 'serves' of a different size.

Page last updated 6 December 2023