Police spokesman Chuck Johnson says the fight occurred Monday night when the Senior Little League game ended and one of the losing team's players was "loud and boisterous" as he left the field.
According to Johnson, a fan of the winning team then punched the player in the head, provoking the teenager's father, Tim Scott of Seminole.
Police say the spectator bit off the Scott's left earlobe and escaped. Scott was treated at Port St. Lucie Medical Center and then released.
Caught in the middle of the brawl was a mother and her 9-month-old daughter, who was knocked from her mother's arms to the ground. Police say the baby was not injured.
No arrests have been made, but an investigation is ongoing and officers are reviewing home videos of the brawl.
The teams were playing in a statewide competition that continued Tuesday night. No incidents were reported at those games.
Port St. Lucie is about 50 miles northwest of West Palm Beach.
Two years ago in Miami, about 20 men charged the field and fought during a baseball game for 4 and 5 year olds. Weeks earlier in Hollywood, Fla., a youth baseball coach broke an umpire's jaw during an argument.