Fish curling in the pan is one of those things people accept as normal. The fillet goes in flat, and within seconds the edges lift, the middle arches, and suddenly only part of the skin is actually cooking.
Most home cooks respond instinctively. They press down with a spatula. They flip the fish early. They turn the heat up, hoping to force it into behaving.
None of that works for long.
To stop fish from curling, it helps to understand why it happens in the first place.
Fish doesn’t cook evenly by default
Fish muscle is delicate and highly structured. As it heats up, the proteins tighten and contract. Skin contracts faster than flesh, which is why the fish begins to pull against itself as soon as it hits the pan.
If heat reaches one part of the fish before another, that contraction happens unevenly. The result is buckling. Once the fish starts to lift, the pan can no longer do its job properly.
At that point, browning becomes patchy and moisture begins to collect underneath the fillet.
Curling is a contact problem, not a heat problem
It’s easy to assume curling means the pan is too hot. Sometimes that’s true, but more often the issue is that the fish isn’t staying in contact long enough for the skin to set before the flesh tightens.
When skin loses contact with the pan:
- Heat becomes inconsistent
- Steam builds underneath
- The skin softens instead of browning
From there, sticking becomes more likely, and the cook starts intervening.
The irony is that most of the fixes people reach for make the curling worse.
Why pressing with a spatula doesn’t help
Pressing fish down with a spatula feels logical, but it’s usually uneven and reactive. The pressure is applied after the fish has already buckled, and it often concentrates force in one spot.
That can tear the skin, push moisture out, or cause the fish to release too early. It also keeps the cook hovering, touching the fish repeatedly instead of letting it settle.
What the fish needs at this stage isn’t force. It needs stability.
How chefs prevent fish from curling
In professional kitchens, fish curling is dealt with before it starts. The fish is placed into the pan carefully, skin-side down, and left alone long enough for the skin to begin setting.
If the fillet shows signs of lifting, gentle, even pressure is applied early to keep the skin flat while the structure firms up. Once that initial contraction has passed, the fish is far less likely to move.
The key difference is timing. Chefs don’t wait for the fish to misbehave before responding.
The role of a fish press
A fish press exists to manage this moment calmly.
Placed on the fish shortly after it goes into the pan, it keeps the skin in contact with the surface while the fish settles into cooking. The pressure is even and passive. Nothing is forced. Nothing is rushed.
By the time the press is removed, the fish has usually done the hard part. The skin has browned, the structure has stabilised, and the fillet is no longer fighting the pan.
At that point, the fish can finish cooking without intervention.
Moisture matters more than most people realise
Curling is often made worse by excess moisture. Wet skin creates steam, and steam weakens the bond between the fish and the pan.
This is why drying fish thoroughly before cooking makes such a difference. Dry skin browns more quickly, which helps it set before the flesh has a chance to pull away.
Josh’s own method is to keep fish on a wire rack over a tray, uncovered, in the fridge for at least a couple of hours before cooking. The moving air dries the surface of the skin without drying the flesh underneath, and the difference in the pan is immediate.
Keeping the fish flat only works properly when moisture is already under control.
When scoring helps — and when it doesn’t
Some cooks score fish skin to reduce curling. This can help with thicker fillets or very tight skin, but it’s not always necessary.
Scoring changes how the skin contracts, but it also affects how it browns and how it looks on the plate. Used carelessly, it can create uneven texture.
Good contact and even pressure often make scoring unnecessary.
Why fish curls when deep-frying — and what to do instead
Deep-frying is the one situation where none of the above applies, and it’s worth being straight about that: a fish press is no use in a deep fryer. There is no pan surface to hold the fillet against, and nothing you can rest on top of fish that is submerged in hot oil.
The cause is the same, though. Skin and connective tissue contract faster than flesh, and in a fryer the heat arrives on every surface at once, so the contraction happens all over in a couple of seconds. That’s why a fillet can go into the oil flat and come out shaped like a taco.
What actually works in a fryer:
- Score the skin side with three or four shallow cuts through the skin only. This is the one place scoring genuinely earns its keep — it gives the contracting skin somewhere to go.
- Batter or crumb the fillet. A coating sets within seconds and holds the shape before the muscle can pull it out of line. It is not a coincidence that battered fish rarely curls.
- Hold it flat for the first few seconds. Lower the fillet in with a spider or tongs and keep light contact until the surface firms, then release. Those first seconds are the whole battle.
- Skin it. For deep-frying specifically, many kitchens simply remove the skin. If the skin isn’t going to end up crisp anyway, it is only there to pull the fillet out of shape.
- Don’t crowd the oil. Too many pieces drops the temperature, which slows the set and gives the contraction longer to win.
If crisp skin is the goal, a pan will beat a fryer every time — because in a pan you can hold the skin flat against a hot surface, and that is the only way skin browns evenly.
Which fish curl the most
Not every fillet behaves the same way. As a rough guide:
- Thin fillets with tight skin curl hardest — whiting, garfish, small snapper, mackerel, sardines. There is very little flesh to resist the pull of the skin.
- Thicker, fattier fillets curl less — salmon, ocean trout, kingfish, larger snapper. The mass of the flesh holds the shape while the skin contracts.
- Fillets with the pin bone line still in can bow along that line as it tightens.
- Very fresh fish curls more than fish that has been aged or rested, because the muscle still has more contractile capacity.
The thinner and fresher the fillet, the more the first thirty seconds in the pan matter.
Let the pan do the work
Once fish curls, the temptation is to interfere. The better approach is to prevent the curl and then trust the process.
Fish that stays flat browns more evenly. Fish that browns evenly releases more cleanly. When that happens, flipping becomes easier, and the flesh stays intact.
The less you fight the fish, the better it cooks.
Common questions
Why does fish curl up when cooking?
The skin and connective tissue contract faster than the flesh as they heat. The skin side shortens, the fillet bows away from the pan, and only the centre stays in contact.
How do I stop fish curling when frying?
Dry the skin thoroughly, get the pan properly hot, lay the fillet in skin-side down, and apply gentle even weight within the first few seconds — before it lifts, not after. Remove the weight once the skin has set.
Should I score the skin?
In a pan, usually not — good contact does the job and scoring can make browning uneven. When deep-frying, yes: a few shallow cuts through the skin help.
Does salting the fish first help?
Salting the skin and leaving it uncovered in the fridge draws surface moisture out, which helps the skin set faster. Salt the flesh side just before it goes in the pan, not hours ahead.
Will a fish weight work for deep-fried fish?
No. A fish weight works by holding a fillet against a hot pan surface. In a fryer there is no surface to hold it against — score the skin or use a coating instead.
A calmer way to cook fish
Fish curling isn’t a sign that you’re doing something wrong. It’s a natural reaction to heat. The difference between frustrating fish and confident fish cooking is knowing how to manage that reaction without panic.
When the fish stays flat, everything else becomes simpler.
The tool in this article
Josh Niland’s Fish Weight is the press used at Saint Peter: 1.6 kg of polished stainless steel, 16 cm across, made to hold a fillet flat without crushing it.