Emergency services were called at 12.20am today to reports of an assault involving three people at the casino.
The 29-year-old man suffered a head injury and was rushed to The Alfred hospital.
A 26-year old Highton man has been charged with recklessly causing injury.
He has been given bail to face Melbourne Magistrates Court in August.
A 29-year old from Colac was also arrested and released pending further investigation.