All the children were admitted to a government-run primary health centre and are said to be out of danger.
The children complained of uneasiness after the meal at the Azampur middle school in Warsaliganj block, about 150 km from here, officials said.
The doctors who examined the children did not find any sign of poison in their bodies.
Samples of the meal have been collected by police for laboratory tests.
Some students informed school teachers that a lizard was found in the mid-day meal served to them.
Last week, around 50 children fell ill after having their mid-day meal at a government school in Sitamarhi district. A lizard was found in the meal.
In the past, lizards, rats, frogs and insects have been found in the meals served to students in the state.
Last year, 23 students died after eating a poisonous meal at a primary school at Dharmasati Gandaman village in Saran district.
A forensic report confirmed the presence of toxic insecticide strains in the cooking oil used for making food at the school.
The mid-day meal scheme is running in 72,000 schools across Bihar, and 16 million students avail meals cooked under the scheme.