It's possible you are thinking of the following:
* The flashback scene in "Harry Potter and the Order of the Phoenix" where Lily and James are arguing about the prophecy: This scene does show a heated argument between Lily and James, but it doesn't depict a physical fight. The scene portrays their disagreement about how to deal with the prophecy and the threat from Voldemort.
* A fan-made scene: It's possible you saw a fan-made scene or artwork depicting a fight between Lily and James. These are not part of the official "Harry Potter" canon.
* The movie "Harry Potter and the Deathly Hallows: Part 2" shows a scene where Lily and James are attacked by Voldemort. This scene, however, doesn't include a fight between Lily and James themselves.
If you have any further details about the specific scene you are looking for, please share them, and I can help you find it.