Fish is one of the few foods where the mainstream advice and the research
actually agree: two portions a week, one of them oily. The complications are
mercury, and knowing which fish are genuinely oily.
Oily fish versus white fish
This distinction does most of the work. Oily fish — salmon, mackerel,
sardine, herring, trout, anchovy — carry omega-3 fats in the flesh itself. These are the fish
behind almost every heart and inflammation headline you have read.
White fish — cod, haddock, sole, tilapia, pollock, snapper — store their
fat in the liver instead. Excellent lean protein, very easy to digest, but not an omega-3
source. Eating cod twice a week does not tick the oily fish box.
Cheapest way to get this right: tinned sardines and
tinned mackerel. Same omega-3 as expensive fresh fish, they keep for years, and the soft
edible bones add calcium you will not get from a fillet.
Mercury, without the panic
Mercury accumulates up the food chain, so big, long-lived predator fish carry the
most. The pattern is simple once you see it.
Highest — limit these
Shark, swordfish, king mackerel, tilefish, marlin, bigeye tuna. Pregnant women, women
trying to conceive, and young children should avoid these.
Moderate — a portion a week is reasonable
Albacore tuna, halibut, sea bass, grouper, snapper, mahi-mahi.
Lowest — eat freely
Sardine, anchovy, salmon, trout, herring, tilapia, pollock, cod, shrimp, prawn, tinned
light tuna. Conveniently, most of the best omega-3 sources sit in this group.
Cooking so the fish is still worth eating
- Deep frying undoes the point. Batter and repeated-use oil cancel a good
part of what made the fish worth eating. Grill, bake, steam or pan-sear.
- Fish is done sooner than you think. When the flesh turns opaque and
flakes with light pressure, take it off. Overcooked fish is dry and most people who "don't
like fish" have mostly eaten it overcooked.
- Acid at the end, not the start. Lemon or vinegar squeezed on before
cooking starts firming the flesh. Add it once the fish is on the plate.
- Fresh smells of the sea, not of fish. A strong fishy smell means it is
past its best. Eyes should be clear, flesh should spring back.
Who should be careful
- Pregnancy: avoid the high-mercury list entirely, avoid raw and
undercooked fish, and stick to two to three portions a week of the low-mercury options.
Omega-3 genuinely matters for foetal brain development, so the answer is choosing better
fish, not avoiding fish.
- Gout or high uric acid: anchovy, sardine, mackerel, herring and roe are
high in purines and can trigger flares, despite otherwise being excellent choices.
- On blood thinners: high-dose fish oil supplements can add to the effect.
Eating fish is a different matter from supplementing — check before you start capsules.
- Shellfish allergy does not automatically mean a fish allergy. They are
separate. Get tested rather than assuming.
This is information, not a prescription. If you are
pregnant, managing a diagnosed condition, or taking medication, talk to your doctor before
making a large change to your diet.
Browse the full list
Every fish below has its own page. Use the filter or the A–Z jump to find one
quickly.