Wenzel says a 15-year-old boy was arrested at a relatives home in Oakland at 2 a.m on Friday. He was arrested without incident.
Police said the motive for the killing was drug related.
Police identified what they called a "person of interest" on Thursday.
Fuchs, who would have graduated from San Ramon Valley High School in June, was shot once in the neck on the front porch of his family's home in the 1000 block of El Captain Drive at about 9:15 p.m. Tuesday.
He died at John Muir Medical Center early Wednesday morning, Lee said.
The homicide was Danville's first since 2007.
Fuchs' step-father, Ron Harmon, told the Danville Weekly newspaper that someone sent text messages to Fuchs' friends right after telling them he had been shot.
Harmon said the messages reportedly said "mess with fire and you'll get burned."