Deadliest Catch Star Charged For Bathroom Assault

According to the criminal complaint obtained by TMZ ... a female witness claims the Discovery Channel reality star got into a fight with her husband ... and it spilled over into the restroom.

When the woman went to check on the situation, she claims she observed that Freddy had her husband in a headlock.

The woman claims she tried to free her hubby, but Freddy grabbed her by the arm and "forcefully" pushed her across the restroom.

When cops arrived to the scene, police say they observed the woman had bruising and swelling on her arm.

According to the complaint, Freddy told police he didn't start the fight ... but was merely defending himself after the other man punched him in the face. Freddy says he "did not touch Katz."

A few days later, a judge ordered Freddy to stay away from the woman, her husband and the hotel. He's due back in court later this month.