Taking a bite of food or a sip of water on a Wuhan subway train could cost you 200 yuan ($32).
The provincial capital of Hubei became the first mainland city to ban eating and drinking on its subway, which opened on Dec 28.
Graffiti, smoking, taking pets onto the train and selling goods are also banned. Violators can be fined up to 200 yuan.
Wuhan subway's Line 2 links the city's two main downtown areas and spans 27 kilometers. It is Central China's first subway and also the first to cross the Yangtze River, the longest river in China.
Eating and drinking on subways are banned in some regions such as Hong Kong.
Many mainland cities discourage eating at subways, but no other city has imposed an official ban.
A similar ban was included in the draft regulation for Shanghai's subways, but it was later excluded after it was rejected at a legislative hearing.
In Beijing, passengers on subway Line 4, which is operated by Hong Kong Mass Transit Railway, are advised not to eat on trains, but no measures have been adopted to enforce that.
The Wuhan regulation is intended to keep the subway clear of strong food odors, for example those associated with some types of instant noodles, according to Zhang Gewen, an official in Wuhan's legislative affairs office, which formulated the regulation.
To help enforce the regulation, 222 staff members from Wuhan Metro, the operator of the subway, have been assigned to various sections, according to Wang Tao, a spokesman for Wuhan Metro.
"We found violations of the regulation are still common," Wang said. "Some people do all sorts of things on subway trains, such as eating, handing out brochures or even washing their faces."
A China Daily reporter saw at least eight people eat snacks or drink on Line 2 over the weekend, and a woman even brought her hamster onto the train.
"I think this regulation should be well implemented. Eating should be banned as it fouls the air in the train and makes it unpleasant for others," said Xue Ling, a Wuhan native.
"We found most passengers follow the regulation and refrain from eating on the train," said a staff member at Wuhan Metro who gave his surname as Tian. "We also check all passengers and stop those who are eating from entering the train."
Wang, the spokesman for Wuhan Metro, said law enforcement members have been dispatched to enforce the ban.
"Although many violations have been found in the past week, we haven't fined anyone, as in most cases the violators are cooperative and stop eating when our law enforcement members explain the regulation to them," he said on Sunday.
"The regulation should act as a deterrent to violations so passengers can get rid of bad habits and get used to a more civilized way of taking the subway," Wang said.