As the Tokyo Metropolitan Government works with industry groups to finalize the date for relocating the famed Tsukiji fish market next year, it is also mulling how to exterminate the hordes of rats infesting the current location.

"Rats won't be spotted in the morning when the market is packed with people. ... But they come out when it's quiet, like on days the market is closed," said Takao Katsumi, a metro government official in charge of inspecting the Tsukiji fish market.

The popular tourist attraction in Tokyo's Chuo Ward has long been a home for rodents that feast off ample fish scraps and nest in the many nooks and crannies.