Bad Girls Club Star Bites Man in Brawl

TMZ broke the story ... Gia was arrested for assault Saturday morning after a violent incident outside of a nightclub.

Now, we've learned ... witnesses told police Gia had been fighting with multiple MEN that night ... including people she had been partying with earlier that evening.

Law enforcement sources tell us ... when cops arrived on scene ... one of the men told cops Gia chomped down on his arm during the ruckus ... and he had a nasty bite mark to prove it.

After talking with witnesses and viewing the bite mark ... cops decided to arrest Gia for assault and battery in the 3rd degree.