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Fish and shellfish


fish steak We should be eating at least two portions of fish a week including one of oily fish. Fish and shellfish are good sources of a variety of vitamins and minerals, and oily fish is particularly rich in omega 3 fatty acids. But if we want to make sure there are enough fish to eat now, and in the future, we need to start thinking about the choices we make when we choose which fish we eat.


Why is fish a healthy choice?


Fish and shellfish are good sources of essential vitamins, such as niacin, and minerals, such as selenium and iodine.

Different types of seafood also give different health benefits. Check out the lists below.

Oily fish
  • includes fish such as salmon, mackerel, sardines, trout and herring
  • is rich in omega 3 fatty acids, which helps prevent heart disease
  • is a good source of vitamins A and D
White fish
  • includes fish such as haddock, plaice, pollack, coley and cod
  • is very low in fat. This means, just like beans and pulses or chicken without the skin, white fish is a healthier low-fat alternative to, for example, red or processed meat that tends to be higher in fat, especially saturated fat
  • contains some omega 3 fatty acids, but at much lower levels than oily fish. See Oily fish, shellfish and omega 3 for more on omega 3 fatty acids
Shellfish
  • includes prawns, mussels and langoustine
  • is low in fat
  • is a good source of selenium, zinc, iodine and copper
  • some types such as mussels, oysters, squid and crab are also good sources of omega 3 fatty acids. (See Oily fish, shellfish and omega 3)
Fish where you also eat the bones
  • includes whitebait, canned sardines, pilchards and salmon
  • help make our bones stronger because they are good sources of calcium and phosphorus
If you want to make the healthier choice, remember to go for steamed, baked or grilled fish or shellfish, rather than fried. This is because frying makes fish and shellfish much higher in fat, especially if they’re cooked in batter.

But this doesn’t mean you need to stop having an occasional portion of fish and chips. Check out Preparing and cooking fish and shellfish for tips on making your fish and chips a healthier option.

But don’t eat too much fish

Although most people should be eating more fish for their health, there are maximum levels recommended for oily fish and crab (and some types of white fish), see How much oily fish? in Oily fish, shellfish and omega 3. Also, again for health reasons, adults should have no more than one portion of swordfish, shark or marlin a week. This is because these fish could contain high levels of mercury.

People who eat a lot of fish every week should try to eat as wide a variety as possible not only for good health but also because of concerns about numbers of fish.

'Pregnancy, children and babies' below contains advice about fish for women who are pregnant, breastfeeding or trying for a baby, and for children and babies.

Do you take supplements?

If you take fish liver oil supplements, remember these are high in vitamin A. This is because fish store vitamin A in their livers. Having too much vitamin A over many years could be harmful.

If you take supplements containing vitamin A, make sure you don't have more than a total of 1.5mg a day from your food and supplements.

Oily fish, shellfish and omega 3


The type of omega 3 fatty acids found in fish (they’re actually called ‘long chain omega 3 polyunsaturated fatty acids’) help prevent heart disease. These fatty acids are also important for women who are pregnant or breastfeeding because they help a baby's nervous system to develop (see Pregnancy, children and babies).

Oily fish such as mackerel, sardines, trout, herring and salmon are the richest source of omega 3 fatty acids. The main shellfish sources are mussels, oysters, squid and crab. Some white fish and other shellfish also contain omega 3 fatty acids but not as much as oily fish.

You can check which fish are oily and which aren't in the table below. And while you’re looking at the lists, have a think about how many of these fish you usually eat. Why not try eating something different?

Oily fishWhite fish
Anchovies
Carp
Eel
Herring (Bloater)
Hilsa
Jack (also known as Scad, Horse mackerel and Trevally)
Kipper (herring)
Mackerel
Orange roughy
Pilchards
Salmon
Sardines
Sprats
Swordfish
Trout
Tuna (fresh)
Whitebait
Brill
Catfish
Cod
Coley
Dab
Dover sole
Flounder
Flying fish
Gurnard
Haddock
Hake
Halibut
Hoki
John Dory
Lemon sole
Ling
Marlin
Monkfish
Pangas (also known as River cobbler, Basa or Pangasius)
Parrot fish
Plaice
Pollack
Pomfret (also known as Butterfish)
Red and grey mullet
Redfish (also known as Ocean perch or Rose fish)
Snapper (also known as Jobfish and Red snapper)
Rock salmon/Dogfish (also known as Flake, Huss, Rigg or Rock eel)
Rohu (also known as Ruhi)
Sea bass
Sea bream (also known as Porgy)
Shark
Skate
Tilapia
Tuna (canned)
Turbot
Whiting
Fresh tuna is an oily fish and is high in omega 3 fatty acids. But when it's canned, these fatty acids are reduced to levels similar to white fish. So, although canned tuna is a healthy choice for most people, it doesn't count as oily fish.

How much oily fish?

Most people should be eating more oily fish because omega 3 fatty acids are very good for the health of our hearts.

However, there are recommendations for the maximum number of portions of oily fish we should be eating each week (a portion is about 140g):
2 portions of oily fish 4 portions of oily fish
Girls and women who might have a baby one dayWomen who won’t have a baby in the future
Women who are pregnant or breastfeedingMen and boys

Why are there limits for oily fish?

Oily fish can contain low levels of pollutants that can build up in the body. The pollutants found in oily fish include dioxins and PCBs (polychlorinated biphenyls). Dioxins and PCBs tend to be found in all foods containing fats. They have no immediate effect on health, but can be harmful because they build up in our bodies over time.

The recommended maximums for oily fish are lower for most girls and women because high levels of dioxins and PCBs in the diet could affect the development of a baby in the future.

If a woman changes her diet when she becomes pregnant, or when she starts trying for a baby, this won't change the levels of dioxins and PCBs that are already in her body. So it's a good idea to limit the amount of oily fish eaten from a young age.

Omega 3 fatty acids are good for a baby's development so pregnant women shouldn't stop eating oily fish (see Pregnancy, children and babies).

So remember, don't give up eating oily fish because the health benefits outweigh the risks as long as you don't eat more than the recommended maximums.

Recent surveys have shown that some other fish, as well as brown crab meat, might also have similar levels of dioxins and PCBs as oily fish.

These fish are: sea bream, sea bass, turbot, halibut and rock salmon (also known as dogfish, flake, huss, rigg or rock eel).

Anyone who regularly eats a lot of fish should consider choosing a wider variety – and avoid eating crab and these five fish too often. Eating a wider variety of fish and shellfish will also help reduce the environmental impact.

Also adults should have no more than one portion of swordfish a week. This is because it could contain high levels of mercury.

Are there enough fish in the sea?


Around the world, some types of fish, especially in certain areas, are threatened by being over-fished. At the same time, we’re eating more fish and shellfish in this country and across Europe. Fish and shellfish farming (and other types of what are known as ‘sustainable aquaculture’) have a significant role to play in meeting our demand for fish and shellfish, along with fishing at sea.

Here are some practical things we can all do when we’re choosing seafood:

  • try to choose fish and shellfish that comes from responsibly managed sources, this means it will have been caught in a way that allows the fish population to continue in the future. Or choose fish and shellfish that has been produced sustainably, this means it will have been farmed in a way that allows the fish population to continue in the future. See below for where to find advice on choosing sustainable seafood.
  • read the labels on fish. These often tell you where the fish comes from as well as what species it is. This can be important because stocks of certain types might be declining in some areas but not in others.
  • look for assurance scheme logos (‘eco-labels’), for example the Marine Stewardship Council’s 'blue tick'.
  • be adventurous – try something new. If you eat fish regularly, try eating a wider variety of fish to help reduce the environmental impact.
For help choosing sustainable seafood check out the following websites:

The Marine Conservation Society (MCS) is a UK charity that offers a viewpoint on the sustainable supply of both farmed and wild seafood. They provide a fish online website containing information on choosing sustainably caught fish: www.fishonline.org

The Marine Stewardship Council (MSC) is a global organisation with standards for assessing the sustainability of fishing. The MSC runs a certification and labelling programme for sustainable wild seafood. The assessments are made by independent third-party accredited certifiers. More about the MSC: www.msc.org

Seafish is an organisation that seeks to promote good quality sustainable seafood, and is funded by Government Fisheries Departments in England, Scotland, Wales and Northern Ireland. See: www.seafish.org

The great majority of the fish caught in the UK is landed in Scotland and The Scottish Government recently launched its ‘Eat more fish’ initiative, which aims to promote the consumption of Scottish Seafood. Its website also provides some useful links to fish sustainability information. See: www.scotland.gov.uk/topics/fisheries/fish

Seafood Scotland is a regional body set up to market, promote and develop responsibly caught Scottish seafood. See: www.seafoodscotland.org

Find out more about what the Government and other organisations are doing about the sustainability of fish at the link below.

Preparing and cooking fish and shellfish


If you fancy being adventurous, why not choose some different types of fish and shellfish that you haven’t cooked before?

Check out the links below for some ideas on how to go about it:


If you want to make the healthier choice, remember to go for steamed, baked or grilled fish or shellfish, rather than fried because frying makes fish and shellfish much higher in fat, especially if they’re cooked in batter.

But this doesn’t mean you need to stop having an occasional portion of fish and chips. If you make your own fish and chips at home or if you love your occasional trip to the fish and chip shop, check out these tips to help make it a healthier choice:

  • have some baked beans, peas or salad with your fish and chips
  • at the fish and chip shop, ask for your food without salt, then add it yourself to taste. You could try having a little less – remember, you can still have plenty of vinegar!
  • go easy with the ketchup and mayonnaise because these can be high in salt and fat. And if you’re eating out, ask for salad dressings or sauces on the side, so you have only as much as you need.
  • have a bread roll with your chips and see if you can manage with a smaller portion of chips, or try sharing them with a friend
  • the thicker the chips the better, because they absorb less fat
  • if the oil is at the right temperature, the fish and chips will not only taste better but they will absorb less fat
  • you could try not eating all the batter on the fish, because this contains a lot of fat

Buying fish and shellfish

Once you've worked out which types you want to buy, try to remember the following when you’re choosing fish and shellfish:

  • buy fish and shellfish from reputable sources. Be wary of people selling seafood out of the boot of their car
  • choose fresh fish or shellfish that is refrigerated or kept on ice
  • don't buy cooked or ready-to-eat fish or shellfish that is touching raw fish or shellfish because cooked and raw food should always be kept separate
  • when you're shopping, pick up fish and shellfish last and take it straight home. Fish and shellfish go off very quickly when they’re out of the fridge

Storing and preparing fish and shellfish

Once you get it back home, remember:

  • put fish and shellfish in the fridge or freezer as soon as you get home
  • make sure that all fish and shellfish are in covered containers but don’t put mussels, oysters or clams or any other live shellfish into airtight containers because they need to breathe
  • don't store fish or shellfish in water
  • discard mussels, oysters or clams or any other live shellfish if their shells crack or break, or if the shells are open and don’t close when you tap them. Live shellfish will 'clam up' if their shells are tapped
  • wash your hands thoroughly before and after handling fish or shellfish
  • don't allow raw fish or shellfish to come into contact with cooked or ready-to-eat food
  • use separate cutting boards, knives, plates, etc. for preparing raw and cooked ready-to-eat food
  • it’s best to thaw fish or shellfish in the fridge overnight, or if you need to thaw it more quickly, you could use a microwave. Use the ‘defrost’ setting and stop when the fish is icy but flexible
  • if you’re marinating seafood, put it in the fridge and throw the marinade away after removing the raw fish or shellfish. If you want to use the marinade as a dip or sauce, set some aside before it touches the raw fish

Avoiding shellfish food poisoning

There are strict rules and monitoring in place that mean all shellfish in the UK should be safe to eat cooked or raw.

However, live shellfish such as mussels, clams and oysters can contain harmful viruses and bacteria when eaten raw or without being thoroughly cooked. These shellfish are filter feeders. This means the water they live in passes through them and they filter their food from this water. So any pollution or germs in the water will build up in the shellfish.

It's also important to take care how you store, prepare and cook all shellfish. So make sure you follow the advice given above in Buying fish and shellfish and in Storing and preparing fish and shellfish.

However, it should be fine to eat all sorts of shellfish that have been thoroughly cooked, because this usually kills any bacteria or viruses in them.

Most of the shellfish we eat is cooked first, but oysters are often served raw, so be especially careful when buying and storing oysters.

Older people, pregnant women, very young children and people who are unwell might want to avoid eating raw shellfish to reduce their risk of getting food poisoning.

Fish and shellfish allergy

Cooking fish or shellfish doesn't make someone with a fish or shellfish allergy less likely to react.

Allergies to fish or shellfish are quite common allergies and can sometimes cause severe reactions. People who are allergic to one type of fish often react to other types as well. Similarly, people who are allergic to one type of shellfish, such as prawns, crabs, mussels or scallops, often react to other types too.

Pregnancy, children and babies


When you're trying for a baby, pregnant or breastfeeding

You can eat most types of fish when you're trying for a baby, pregnant or breastfeeding. Eating fish is good for your health and the development of your baby. But you just need to avoid some types of fish and limit the amount you eat of some others.

This table shows the maximum number of portions you should have each week for the fish you need to limit.

  Trying for a baby Pregnant Breastfeeding
oily fish 2 portions 2 portions 2 portions
tuna 2 tuna steaks or 4 cans 2 tuna steaks or 4 cans 2 tuna steaks or no limit on cans
shark, swordfish and marlin don't eat don't eat 1 (same for all adults)

The figures for tuna are based on tuna steak weighing 140g when cooked or 170g raw and medium-size cans with a drained weight of about 140g per can.

Canned tuna doesn't count as oily fish, so you can eat this as well as your maximum two portions of oily fish. If you’re eating canned tuna, don’t pick fresh tuna as your oily fish. And if you eat two tuna steaks in a week, don’t eat any other oily fish that week.

When you’re totting up your weekly portions of oily fish, you’ll need to include a few other types of fish (as well as crab) because they might have similar levels of dioxins and PCBs as oily fish. These fish are: sea bream, sea bass, turbot, halibut and rock salmon (also known as dogfish, flake, huss, rigg or rock eel).

The limits for shark, swordfish, marlin and tuna are because these fish contain more mercury than other types of fish. The amount of mercury we get from food isn't harmful for most people, but if you take in high levels of mercury when you're pregnant this could affect your baby's developing nervous system.

Oily fish are very good for our health, but we need to limit how much we have because they contain pollutants. These pollutants have no immediate effect on health, but can be harmful if they build up in our bodies over time.

Omega 3 fatty acids are good for a baby's development so don’t stop eating oily fish. If you change your diet once you’re already pregnant this won't change the levels of the pollutants that are already in your body. You just need to stick to the limits shown in the above table.

Unless your GP advises otherwise, you should avoid taking fish liver oil supplements when you’re pregnant or trying for a baby because these are high in vitamin A, which can be harmful to your unborn baby.

When you're pregnant you might also want to avoid eating raw shellfish. This is to reduce your chances of getting food poisoning, which can be particularly unpleasant during pregnancy.

See the links below for more advice about what foods you should avoid.

Children and babies

Don't give any fish or shellfish to babies younger than six months because these foods can trigger the development of a food allergy at this age.

Children should avoid eating any shark, swordfish or marlin. This is because the levels of mercury in these fish can affect the development of children's growing nervous systems.

You might also want to avoid giving raw shellfish to babies and children to reduce their risk of getting food poisoning.