The fishermen were taken into custody on Tuesday by the Maritime Security Agency, which also seized three boats, officials said.
They were handed over to police in Karachi after interrogation and an FIR was registered against them under the Foreigners Act, they said.
A total of 61 Indian fishermen were arrested by the MSA for allegedly fishing in Pakistani waters last month. Pakistan arrests scores of Indian fishermen every year.
The two countries recently agreed to work on measures for the expeditious release of people who inadvertently cross land or maritime boundaries.