A boat owner has scorned a group of "coward punks" after they shoved him into a canal when he confronted them over kicking two swans in East London on Monday.
A video shared on Twitter shows the group gathered around a pair of swans and one girl lowering her leg to kick the birds, who swim away.
Boat owner and teacher Jeffery Phillips told MailOnline he witnessed one of the boys throw a fully loaded Fanta bottle, hitting one of the swans.
"You can't do this, these birds are a protected species," the 55-year-old said.
But when Phillips approached the group, the next thing he knew he was swimming in the water with them.
"The guy who pushed me was nothing but a coward, as are the rest of them," Phillips said.
The group appear to argue with Phillips as he stands in waist-high water before they leave the scene.
The boy who pushed Phillips can be heard in the footage shouting: "Have that!"
"The water isn't deep but it's really manky. It was embarrassing, it was frustrating but then everybody disappeared," Phillips said.
Metropolitan Police Superintendent Andy Cox said the incident was unfortunate.
"Awful viewing. Animal cruelty is an indicator of many other vile behaviours and a tendency towards other forms of violence."
But some witnesses say the girl intervened to stop the swans from fighting.
"The girl was trying to separate the swans to avoid one of them being killed," one witness said.
Another witness said the swans were wrestling for four or five minutes, with one swan trying to drown the other.
A bystander also at the scene said a woman was "screaming" at the swans to stop before the girl intervened, attracting a crowd of people.
Phillips has lived in his houseboat for 12 years and claims the group have targeted him before.
Local police are investigating the incident.