Four "geckos" - a type of endangered lizard - on Thursday went missing from their enclosure at the Alipore Zoological Garden here, raising fears they could have been stolen.
An official said the enclosure housing 11 of the reptiles was broken by pouring acid on the lock.
Later in the day, seven geckos were found from in and around the enclosure.
Urban Development Minister Firhad Hakim, who visited the zoo during the day, said an attempt was made to break the enclosure and steal the reptiles.
The zoo authorities lodged a complaint with the Watgunge police station.
In April 2009, eight brazilian monkeys or marmosets were stolen from the zoo.
The gecoks were brought to the zoo in late 2013 after they were caught by the Border Security Force while being smuggled out of the country.
The animals were later handed over to the forest department which gave them away to the zoo.