They’re affected by spiralling costs like everyone else, but to a greater degree (cooking oil, energy, cod etc) so they have to open when they know there will be trade.
The cost of a ‘fish supper’ these days is too high for many compared to the cheap meal it always used to be, so trade is down. To us, its very much an occasional treat now only. Many chip shops, like pubs simply can’t make enough profit and are closing. Sign of the times.