Nearly 90 monks at Sasar Muayroy Pagoda in Kratie province suffered severe food poisoning after they ate fish stew for breakfast on Monday.
None of their lives were endangered, but Chhneang Sovutha, chief of Kratie provincial health department, said 35 out of 85 monks affected had severe symptoms and were sent to a local health centre.
He said the cook had prepared porridge for the monks with fish stew, using many different kinds of fish, some of which were poisonous.
The monks who ate it almost instantly showed symptoms, including dizziness, nausea, and vomiting.
The incident led the provincial health department to ask the Ministry of Agriculture, Forestry and Fisheries to educate people about the species of fish that could harm the health of the general population.