Interactive lesson

Salt fish, step by step

Interactive lesson: ice, gutting and freezing — salt sardines in saturated salt, cured trout, salted roe and soaking salt cod.

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The whole lesson as text

1. From catch to salting

Fish is salted while it's cold: ice at once, gutting the same day.

Ice at once — Fish goes into a cool box or bucket with crushed ice and a little seawater, fish and ice half and half. Never into a bag in the sun.
Gutting the same day — With sardines and anchovies, pinch off the head with your fingers and pull the guts out with it. Open larger fish along the belly with a knife and scrape out the dark membrane and blood along the spine.
Bleeding — Put cleaned small fish in a cold 5 % brine (50 g of salt per 1 L of water) in the fridge for 1–2 hours. The flesh turns paler and firmer.
Cold and weighing — Keep the fish at 0–2 °C until salting. Weigh it and write it in the log: the amount of salt depends on the weight.

Why: Oily fish (sardine, anchovy, herring, mackerel) left in the warm forms histamine within hours. Histamine can't be seen, and neither salt nor cooking destroys it. Type E botulism lives in mud and fish guts and grows from as low as 3 °C (38 °F).

Oily fish must not sit in the warm even for an hour. Sardines and anchovies spoil within half a day in summer heat.
Don't salt ungutted fish at home: ungutted salted fish is a known cause of botulism.

2. Parasites and freezing

Fish eaten without cooking is frozen first.

Where parasites are — Anisakis is often in the guts and belly of sea fish. So gut the fish at once, then freeze any fish that will be eaten uncooked.
Freeze for 7 days — Keep fish or fillets up to 5 cm (2 in) thick, in a bag, at −18 to −20 °C (0 to −4 °F) for at least 7 days.
Check the freezer — Your home freezer must really hold −18 °C. Check it with a thermometer.
Thaw in the fridge — Thaw frozen fish in the fridge, not on the worktop.

Why: Sea fish can carry anisakis, carp-family fish flukes, and pike and zander tapeworm. Freezing kills them; salt and vinegar don't do it reliably. Cooking or baking to 63 °C (145 °F) in the centre kills parasites for sure.

Small white worms in the belly of a fish are anisakis: cut away the belly and eat the rest only frozen or cooked.
Pregnant women, small children, the elderly and the ill eat salt fish only cooked or baked.