The man was arrested after the teenager attacked armed adults on the beach Devon, the police said.
Devon and Cornwall Police initiated an investigation After attack that took place during the “great disorder”.
Officers were invited Return of the beach in Teigmouth on Friday around 8.45pm, where 50 to 100 teenagers and adults were present.
Now identified a teenager who suffered less head injuries.
Records of the attack circulate on social media, which force called people not to share online.
Detective Sergeant Emma Boobyer, from Devon and Cornwall police, added, “We identified a teenage girl who suffered less head injuries.
“He was checked in the hospital and fired.”
The man was arrested under suspicion of afraccation and remains in police custody, said force.
DS Boobyer said, “We are aware of a recording that circling social media and possible names identified.
“Please do not share these recordings, and we must remind the public that every suspect under the age of 18 is not allowed to identify.
“These rules are not exclusively that media organizations do not comply.
“They also refer to public members and includes information published through social media.
“This can be considered by hiding live investigation, so we remind the public that it is vital that they do not speculate about the identity of any suspects in this case.
“If you have any information, report it directly to us.”
The force said that the presence of police in the area will be enhanced during the weekend.