How to poach fish
The short answer
Poach fish in liquid held at a bare simmer, around 70 to 80C with just a shiver on the surface, for 6 to 10 minutes depending on thickness, until the flesh is just opaque. Use a court bouillon of water, wine and aromatics, or milk for smoked haddock and delicate white fish. The liquid should never boil, since a rolling boil breaks the flesh and toughens it.
Step by step
1. Make the poaching liquid. For a court bouillon, simmer water with a splash of white wine, a sliced onion, a bay leaf, peppercorns and a little salt for 10 minutes, then let it settle. For milk-poached fish, use plain milk with a bay leaf. 2. Bring the liquid to a bare simmer. You want the surface to tremble with the odd bubble rather than a steady boil. 3. Lower the fish in gently so it is just covered by the liquid. 4. Hold it at that bare simmer, adjusting the heat so it never boils:
- Fillets 2 to 3cm: 6 to 8 minutes.
- Thick cuts and small whole fish: 8 to 12 minutes.
5. Check for doneness. The flesh turns from glassy to just opaque and flakes cleanly, reading 55 to 60C on a probe. 6. Lift the fish out with a slotted spatula and drain it. 7. For cold poached salmon, take the pan off the heat just before the fish is done and let it cool in the liquid so it finishes gently and stays moist.
Which fish it suits
Poaching suits fish that you want tender and clean-tasting. White fish like cod, haddock and pollock hold together well. Smoked haddock poached in milk is a classic, and the milk becomes the sauce. Salmon and trout poach beautifully and are lovely served cold. A whole salmon can be poached for a cold platter.
Very thin flat fish fillets cook in a minute or two and overcook fast, so keep the liquid gentle and lift them early. Oily and firm fish poach fine and stay moist.
Tips / common mistakes
- Never let the liquid boil. A bare simmer is the whole technique. Boiling shreds the flesh and dries it.
- Just cover the fish with liquid so it cooks evenly.
- Milk suits smoked haddock and delicate white fish, and doubles as the base for a parsley sauce.
- Save the strained poaching liquid to build a sauce or a soup base.
- For cold poached salmon, cool it in the liquid so it stays moist and takes on the aromatics.
Frequently asked questions
What temperature do you poach fish at? Around 70 to 80C, a bare simmer where the surface just trembles. Keep it below a rolling boil throughout.
Do you poach fish in water or milk? Both work. A court bouillon of water, wine and aromatics suits most fish, while milk is traditional for smoked haddock and gentle white fish and makes a ready sauce.
How long does it take to poach fish? About 6 to 8 minutes for a fillet and 8 to 12 for a thick cut or small whole fish, at a bare simmer, until just opaque.
Can you poach fish from frozen? Defrost it first for even, gentle cooking. Poaching is a delicate method and frozen fish can go from underdone in the middle to overdone at the edges. Defrost overnight in the fridge.
Can you reuse the poaching liquid? Yes. Strain it and use it the same day as a base for sauce, soup or risotto, or freeze it for stock.
For a gentler method still, read how to steam fish.
