Fish for babies: when to start, mercury, bones and how much

Babies can eat fish from around 6 months, as one of their first foods. Cook it thoroughly, remove every bone, and choose lower-mercury fish most of the time. The NHS guide to feeding from around 6 months lists fish (with no bones) among the protein foods suitable from this age, and shellfish too, as long as it isn't raw or lightly cooked.

Fish and shellfish are also common allergy foods. Australia's ASCIA's guide to introducing solid foods includes them in the list of foods to introduce in the first year (by 12 months) and then keep in the diet regularly. This guide covers which fish to limit, how to cook and serve fish at each stage, how much to offer, and what to do if your baby reacts or chokes.

When can babies eat fish?

From around 6 months, once your baby has started solids. The NHS includes fish among the foods that can trigger allergic reactions and can be introduced from around 6 months, one at a time. Australia's ASCIA lists fish among the iron-rich foods to offer from around 6 months, and suggests strips of fish as a finger food when your baby is ready. Australia's Pregnancy, Birth and Baby lists puréed fish among first foods, and soft cut-up fish with no bones among the finger foods most babies manage at about 8 months.

Fish brings more than protein. Food Standards Australia New Zealand describes fish as an excellent source of protein, essential omega-3 fatty acids and iodine. The FDA's advice about eating fish adds iron, zinc, vitamin B12, vitamin D and selenium, and says the omega-3 fats in fish support brain development. See iron-rich first foods for how fish fits alongside meat, egg and legumes.

Which fish should babies avoid or limit because of mercury?

Some fish carry much more mercury than others. FSANZ says high mercury levels can damage the nervous system, and that children are especially vulnerable because they are growing quickly. The NHS list of foods to avoid says the mercury in shark, swordfish and marlin can affect the development of a baby's nervous system.

The lists differ between countries, so follow your own country's list. The FDA's lowest-mercury "best choices" include salmon, sardines, cod, haddock, hake, pollock, tilapia, whiting, trout, canned light tuna and shrimp (prawns). If family or friends catch fish locally, the FDA suggests checking local advisories, or eating only one serving and no other fish that week if there's no advisory.

How do I prepare fish for my baby at each age?

Cook fish thoroughly. The CDC's safer food choices for children under 5 says to cook fish to 63°C (145°F) or until the flesh is opaque and separates easily with a fork. Then check carefully for bones: the CDC's choking hazards list includes bones in meat or fish.

A few practical points:

1. Bake, steam, poach or grill fish without added salt. The NHS says babies shouldn't eat salty foods because they're not good for their kidneys.
2. Mash canned fish well. The NHS fish and shellfish page says canned sardines, pilchards and tinned salmon contain bones you can eat; mash them in thoroughly and remove any that are still firm. Choose fish canned without added salt.
3. Cook shellfish fully. The CDC says to cook shellfish until the shells open or the flesh is pearly or white and opaque. Chop prawns and similar shellfish finely.
4. Let it cool before serving, and serve it in a texture your baby already manages. See food textures by age.

Can babies eat raw fish, smoked fish or shellfish?

Raw and lightly cooked seafood carries a higher risk of food poisoning, and young children are more vulnerable. The CDC lists raw or undercooked fish and shellfish, including sashimi, sushi and ceviche, as riskier choices for children under 5, because their immune systems are still developing.

• Raw or lightly cooked shellfish. The NHS says to avoid giving raw shellfish such as mussels, clams and oysters to babies and young children, because of the risk of food poisoning.
• Smoked fish. The FSANZ guide to food safety for vulnerable people lists smoked seafood and chilled cooked prawns as higher-risk ready-to-eat foods for groups including newborn babies, and suggests freshly cooked or thoroughly reheated seafood (steaming hot) instead. If you offer smoked fish, cooking it into a hot dish follows that advice.

How often can babies and toddlers eat fish?

None of the sources we checked gives a weekly fish amount specifically for babies under 12 months, beyond the limits on high-mercury fish above. For young children:

• US. The FDA suggests 2 servings a week from its "best choices" list for children aged 1 to 11, with a serving of about 1 ounce (about 30 g) at ages 1 to 3.
• UK. The NHS guide to feeding young children suggests at least 1 portion of oily fish, such as mackerel, salmon or sardines, a week. Boys can have up to 4 portions of oily fish a week and girls no more than 2, because pollutants can build up in the body. The NHS says fresh and canned tuna don't count as oily fish.
• Australia. FSANZ sets a child's portion at 75 g for its limits on shark, billfish, orange roughy and catfish.

Rotating different lower-mercury fish through the week is an easy way to stay within these limits.

How do I introduce fish as an allergen?

Introduce fish and shellfish separately, each on its own, as you would other common allergy foods. Offer a small amount when your baby is well and you can watch them for a couple of hours, since Australia's ASCIA says reactions usually happen within minutes to two hours. If there's no reaction, offer more next time and keep it in your baby's diet at least once a week.

Australia's ASCIA's seafood allergy FAQ says seafood allergy is more common in teenagers and adults than in very early childhood. Fish and shellfish allergens are quite different, so a person can be allergic to fish only, shellfish only, or both. Introducing allergens has the full plan.

What should I do if my baby reacts or chokes?

Australia's ASCIA's anaphylaxis FAQ lists hives or welts, swelling of the face or eyes, and vomiting as mild to moderate signs. If you see these and your baby is breathing normally, stop giving that food, stay with your baby, watch closely for signs of anaphylaxis and get medical help today. Australia's ASCIA says to get specialist advice before offering it again. Redness only around the mouth, with no other signs, is not usually an allergic reaction.

Follow the Australia's ASCIA first aid plan for anaphylaxis, and start CPR if your baby is unresponsive and not breathing normally. Australia's ASCIA classes lip swelling as a mild to moderate sign, while the NHS urgent-help guide lists swollen lips among the reasons to call an ambulance, so this guide treats sudden lip swelling as an emergency.

If your baby is choking and can't breathe, cough or cry, shout for help and call 999. The NHS first-aid steps for a choking baby are up to 5 back blows, then up to 5 chest thrusts, repeated until help arrives; if your baby becomes unresponsive, start CPR and follow the call-taker's instructions. Get medical help afterwards, even if the food came out. Choking vs gagging walks through each step. The Royal Children's Hospital Melbourne in Australia recommends that anyone caring for children does a first-aid course.

What's worth noting when you offer fish?

A short note of the type of fish, how it was cooked and roughly how much your baby ate makes it easy to rotate low-mercury fish through the week and keep track of the allergy foods already tried. If your baby reacts, note the time, the fish and what you saw; a photo of any rash helps the doctor.

When should I get help?

Call 999 now if your baby:

• has difficult or noisy breathing, a wheeze or a persistent cough
• has sudden swelling of the lips, tongue or throat
• has a hoarse voice or cry, or becomes pale, floppy or drowsy, or collapses
• is choking and can't breathe, cough or cry
• has had no wet nappy or wee for 12 hours

Get medical help today if your baby:

• has hives or welts beyond the mouth area, or swelling of the face or eyes, with normal breathing (stop the food and watch closely for anaphylaxis signs)
• vomits after eating fish or shellfish
• needed back blows or chest thrusts, or you think a piece of bone may still be stuck
• has diarrhoea or vomiting with fewer wet nappies than usual (see signs of dehydration)

Talk to your GP or health visitor if:

• your baby has reacted to one fish or shellfish and you'd like advice on others
• your family eats a lot of locally caught fish and you're unsure about mercury
• you have questions about fitting fish into a vegetarian or restricted diet (call NHS 111 after hours)