The victim, 79, almost drowned after he was allegedly pushed into the water off Mornington Pier on Monday.
Police arrested a 17-year-old Hastings boy in connection to the incident overnight and will likely charge him at a later date.
The attack occurred at a pier off Schnapper Point Drive, about 50 kilometres south-east of Melbourne.
It’s believed the man was pushed into the water, with the alleged attack filmed and then later posted to social media.
The man had to be rescued by nearby strangers and was not injured.
Police yesterday charged a 14-year-old boy with reckless endangerment and unlawful assault.
Both teenagers will face a children’s court at a later date.
