The deceased has been identified as Mohamad Farhan. He had gone to the Powai lake for fishing with his friends this afternoon, a senior police official said.
The officer said as per Farhan's father, he had fits problem.
Farhan slipped off the tube they were riding on and fell into water after suffering from one such fits bout, the officer said, adding his body was later fished out.
A case has been registered and a probe was on, said police.