Fish and curing salt: Why this is dangerous

Why is this even a problem?

Curing salt (pink salt) contains sodium nitrite (E250), which works great for curing meat: it inhibits bacteria like Clostridium botulinum, creates the typical pink color, and delivers that classic cured flavor. Sounds good — but fish reacts differently to the chemistry.

Fish naturally contains high levels of biogenic amines (e.g., histamine) and secondary amines from protein breakdown. These amines react with nitrite — especially under heat or long curing times — to form N-nitrosamines, which rank among the most likely carcinogenic compounds. This risk is especially high when you smoke or fry cured fish, since heat dramatically accelerates nitrosamine formation.

On top of that, fish cures much faster than meat. A salmon fillet 1–2 cm thick is ready in just a few hours. If you simply copy the quantities from a meat recipe, you'll likely use way too much nitrite.

How to do it right

• Basic fish curing (gravlax, brining): Use only plain sea salt or rock salt — 30–50 g per kg of fish. No curing salt needed, no risk.
• Cold-smoking fish (e.g., salmon, mackerel): Curing salt can make sense here, but only for very long smoke sessions below 25 °C. If you use it at all, stick to a maximum of 0.4–0.5% curing salt by fish weight — and keep the curing time as short as possible.
• Curing temperature: Always cure in the fridge at 2–4 °C. Never at room temperature — that accelerates both protein breakdown and nitrosamine formation.
• Hot smoking: Skip the curing salt entirely. When hot-smoking above 60 °C, nitrite + fish protein will almost certainly produce nitrosamines. The heat itself is your protection here — no curing salt needed.
• Control your curing time: Thin fillets (2 cm) max. 4–6 hours, thicker cuts (5 cm) max. 12–18 hours. Rinse off the salt afterwards and let the fish dry thoroughly.

Bottom Line

With fish, the rule of thumb is: sea salt instead of curing salt — and if you do use curing salt, only for cold-smoking, dosed carefully, and always at low temperatures.