HARTLEPOOL, England — When it opened in 2020, business was booming at Chunks, a store serving dozens of portions each day of Britain’s best known takeout meal: battered and deep-fried cod with fries, or chips as they are known here.

But even before the war in Ukraine further pushed up the shop’s bills for energy, fish and cooking oil, inflation had already forced the owners, Sayward and Michael Lewis, to raise their prices twice.

Now, with another spike in prices driving away customers, Chunks is on the brink of failing.

“We might not be able to make it to the end of the month,” said Ms. Lewis, sitting in the back of the store in Hartlepool, a port town in northeastern England where her husband, Michael, was raised.

The fighting in Ukraine is, Ms. Lewis added, “the straw that broke the camel’s back” — and not just for Chunks, but possibly for thousands of other fish-and-chips shops up and down the country.

The war, which has devastated cities in Ukraine and killed thousands, has in Britain piled more pressure on a sector that was already struggling with pandemic-related inflation. Costs of gas and electricity have surged. The price of cod has risen after countries announced plans to ban or penalize Russian fish imports, making North Sea supplies scarcer and pricier.

Ukraine and Russia are large producers of sunflower oil, used by many fish-and-chips shops, and that is running out. And even potatoes are destined to become more expensive, as rising gas prices push up the cost of fertilizer.

“My industry is directly affected by the Ukraine issue because all our four main ingredients are directly affected, and we use a lot of them,” said Andrew Crook, the president of the National Federation of Fish Friers, referring to fish, oil, flour (for batter) and potatoes.

As a result, Britain stands to lose perhaps as many as 3,000 of its approximately 10,000 fish-and-chips shops, according to Mr. Crook, who describes the situation as the industry’s biggest crisis since such stores first opened in the 1860s.

More than 150 years later, at least one store — or “chippy” — is to be found in most towns of any size, churning out an inexpensive takeout meal that inspired the British idiom “cheap as chips.”

Not any more.

To add to the gloom, and higher prices, the government recently ended a reduced rate of sales tax on takeout food that it had applied as a pandemic measure.

When the Lewises opened Chunks, they assumed a fish-and-chips business was a safe bet. After all, it was a product deemed so important to morale that it was never rationed during World War II — a culinary combination referred to by Winston Churchill as the “good companions.”

But as inflation squeezes their incomes, some of their customers have reacted to the increased prices with anger or even abuse, while others have stayed away. Costs have even risen for preparing mushy peas, a gooey green side dish. After the last price hike, sales at Chunks fell by 1,000 pounds, or about $1,300, in a week.

“I feel as though the things that are happening externally are now going to stop us because it’s out of our control: The only thing we can do is to raise prices but people won’t pay,” said Mr. Lewis, who went back to his old job as an electrical inspector to keep money coming in.

A short drive away, things are even worse for Peter Weegram, who, after a quarter-century, recently closed his store and laid off two workers.

Mr. Weegram said he felt sick when he shuttered his shop, The Chippy, concluding that he could no longer make a living. He still hopes that fish prices will fall enough for him to reopen.

“I’m climbing up the walls now — I’ve never been unemployed in my life,” he said at his empty shop.

Within two weeks, the cost for boxes of cod he bought increased to £185 from £141, while his gas and electricity bill almost doubled, meaning he would have had to raise his prices for a single serving to about £9 from £5.60 just to break even.

“People around here wouldn’t have paid it,” he said, adding that fish and chips “used to be a cheap meal and now it will end up as a luxury.”

A few miles south, in the seaside town of Redcar, Nicola Atkinson is determined that her store, Seabreeze, will survive, but she is also feeling the pinch.

“I’ve been doing this for 25 years — I have never seen anything like it,” she said as she explained how she had raised prices for the fourth time since the beginning of last year.

“How do you keep explaining that to customers?” she asked. “People don’t have the disposable income, so what are they going to do? Are they going to come less? We can’t afford not to put the prices up because we would be running at a loss, and then we would not be here for tomorrow. But there is a cap on what people can afford to spend.”

Some customers in England’s northeast still think fish and chips is worth the higher price.

“It’s a British staple,” said El Jepson, a nail technician who frequents Chunks. “Who doesn’t eat fish and chips?”

But in Redcar, David Bell was less sanguine. “Two pounds fifty for a bag of chips? You could buy a sack of potatoes for that.”

A staple of working-class life across their long history, fish-and-chips shops are expected to be cheap but must compete with chains whose primary offerings — burgers, fried chicken and pizza — are typically less costly than fish.

“Prices are already at a record high, they’re going up between 5 and 10 percent each week,” said Mr. Crook, of the federation of fish friers. Britain buys relatively few fish from Russia — and has threatened to add significant tariffs on those — but Mr. Crook said that a United States ban on Russian fish imports had increased competition for supplies from Iceland and Norway, which fish-and-chip shops rely on.

Mr. Crook runs a chippy in Euxton in Lancashire where his last supplies of Ukrainian sunflower oil are stacked in the front. When that runs out, he might opt for palm oil, but other food producers are also seeking supplies, sending prices up.

While Mr. Crook is confident he can survive financially, he is certain many other store owners will not. And he said Britain would lose more than takeout meals if thousands of neighborhood chippies disappeared.

“There’s a bit of theater in a fish-and-chip shop, it’s bit like being behind a bar,” Mr. Crook said. “I’ve got customers that just come in for the banter and, for some of the older people, we might be the only people they speak to all day.”

He added, “It’s something special, it’s part of the culture of the nation.”