How do I barbecue fish without it sticking to the grill?

Fish sticks because its proteins bond chemically with hot metal — the same reaction that makes a steak stick, but fish has far less connective tissue holding it together, so when you pull, the fish tears rather than the bond. Everything below is about either preventing the bond or waiting for it to release on its own, which it does.

Safety

What you'll need

• A wire brush and a folded cloth
• Oil, and a brush or paper to apply it
• A wide fish slice or two
• A fish cage or grill basket (optional)

Step by step

1. Choose fish that can take it.Whole fish on the bone — mackerel, sardines, sea bream, trout — is the easiest thing on a barbecue, because the skin and skeleton hold it together. Thick oily fillets and steaks — salmon, tuna, swordfish, monkfish — are next. Thin white fillets are the hardest and are honestly better cooked another way.
2. Clean the bars while they are hot, then heat them again.Burn off residue, brush hard, then let the grate come back to full heat. Old carbonised food is what fish grips onto, more than the metal itself.
3. Oil the fish, not the grate.A film of oil on hot bars burns off in seconds and produces flame. Brush or wipe the fish itself with a high smoke point oil — rapeseed, groundnut, sunflower — on every surface that will touch metal.
4. Wait for the bars to be properly hot before the fish goes on.A hot surface sears the outer layer and creates the crust that releases; a warm one lets the proteins settle into the metal. Counter-intuitively, more heat means less sticking, not more.
5. Lay it down and do not touch it.Not to check, not to reposition, not to nudge. The bond forms and then breaks by itself as the crust sets. Every early lift tears the surface off and leaves it behind.
6. Test for release rather than turning on a timer.After three or four minutes, slide a thin fish slice under one edge. If it resists at all, leave it another minute. When it is ready it lifts cleanly with almost no pressure.
7. Turn once, using two slices for anything large.One to lift, one to support. Tongs are for whole fish and skewers only — on a fillet they concentrate all the force in one spot and it breaks there.
8. Use indirect heat for the second side, or for anything thick.Sear over the coals, then move it to the cooler side with the lid on to finish. That stops the outside charring while the middle catches up, especially on whole fish.

Tips

• A hinged fish cage is the single best barbecue accessory for fish. It solves sticking and turning at once and costs very little.
• Wet cedar or oak planks are excellent for salmon fillets — the fish never touches metal, it smokes gently and there is no turning at all.
• A bed of lemon or orange slices under a fillet works as an edible non-stick layer and flavours it at the same time.
• Score whole fish twice on each side down to the bone. It cooks more evenly and the skin is less likely to burst and stick.
• Salt whole fish inside and out fifteen minutes before it goes on and pat it dry again — it firms the skin and helps it hold together.

Common mistakes

• Putting fish on a barely warm grate — The classic error. People fear burning it so they wait for the coals to die down, and a cool surface is precisely what causes fish to weld itself on and tear.
• Moving it in the first few minutes — The crust that lets fish release has not formed yet. Lifting early tears the skin off, and once the skin is gone the flesh sticks even harder for the rest of the cook.
• Marinating fish in a sugary or sweet glaze from the start — Sugar burns and glues. Apply anything sweet — teriyaki, honey, barbecue sauce — only in the last minute or two, and away from direct flame.

If it doesn't work

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