Tila Tequila: She's Not Fit to Raise Our Daughter ... Baby Daddy Claims

Tila Tequila is not mentally stable enough to continue calling the shots for her daughter ... according to the kid's father.

Thomas Whitaker is fighting for full legal custody of 1-year-old Isabella, and wants to make all decisions for the little girl. He claims Tila has delusions of grandeur ... such as believing she's God.

Thomas says they don't have a formal custody arrangement right now. He's asking the court to grant him child support, and change Isabella's last name from Nguyen (Tila's real last name) to Whitaker.

He's also requesting some new ground rules: no booze for Tila 24 hours before she gets Isabella and while she has her -- plus, no bad-mouthing dad.