The New Seaway Fish Market, a fixture in Toronto’s Kensington Market, will reopen its doors Friday morning with new inventory after a rat infestation closed the fishmonger for several days.

“I’m really shocked,” proprietor Kim Chou told the Globe and Mail.

“This building is at least 100 years old, and gradually it got damaged. I have to say I didn’t really pay attention – that’s why the rats found entry to my store.”

The intruders were Norway rats, brown and sleek, and there were probably dozens of them on or around the premises, said Jim Chan, who manages the food safety program for Toronto Public Health.

In recent weeks, Mr. Chan’s staff have closed three other rodent-plagued food outlets downtown – one in Kensington, another on Spadina Avenue and a third on Gerrard Street – and he explains that what’s going on is no great mystery. It’s the rapidly changing weather, coupled with rats’ talent for crawling through extremely small holes. “When it’s cold, rodents such as rats like to burrow into structures, to wherever it’s warm.”

Then, when things warm up, they’re on the move again. “It all makes them mobile.”