Police say it happened at an apartment complex on Alamos and Woodrow near Fresno State around 3 a.m. Wednesday.
Officers arrived to find the 21-year-old victim with a stab wound to his upper arm.
The victim was taken to the hospital and is expected to be okay.
Officers say the victim and his 25-year-old brother, Juan Gonzalez, were involved in an argument.
That's when they say Gonzalez pulled out a kitchen knife and stabbed his younger brother.
Gonzalez was the one to flag down officers and was taken into custody for assault with a deadly weapon.