A man was assaulted while riding on the dodgems with his family at Brighton Marina.
The 32-year-old victim broke his ankle in the attack, which happened at about 2.30pm.
He told police officers he was about to get out of his dodgem he was head-butted by another man, causing him to fall backwards and break his ankle.
The attacker was with a younger woman, two small children and an older woman who is alleged to have pushed the victim in the chest.
They then all walked off eastbound towards the restaurants at Marina Village.
The man who is alleged to have assaulted the victim is described as being of Asian ethnicity, 30-35, 5' 7" to 5' 8" of slim build and was clean shaven with short black hair.
Anyone with information contact Sussex Police on 101 quoting 767 of March 3 or Crimestoppers anonymously on 0800 555 111.