"It is with great sorrow that we must say goodbye to Tony Sly of No Use For A Name," said the label's website. "We received a call earlier today of his passing, and are devastated. We have lost and incredible, talent, friend, and father - one of the true greats."
Fat Mike, Fat Wreck Chords founder, NOFX lead singer and Sly's friend, also released a statement.
"One of my dearest friends and favorite songwriters has gone away too soon. Tony, you will be greatly missed," said Fat Mike, whose real name is Mike Burkett.
Tony Sly joined No Use For A Name in 1989, two years after the San Jose, Calif., group's inception. He appeared on nine of its albums, according to Spinner. He also released several of his own solo records and most recently appeared with NUFAN on the band's 2008 album "Feel Good Record of The Year."
Chris Shiflett was a member of the band before joining Dave Grohl and the Foo Fighters.
Sly's cause of death isn't yet known, but in June he gave an interview to Spinner where he revealed he'd been having problems in his lower back, more specifically a herniated disc. He detailed his trips to the chiropractor and said going onstage required he take medication and "have a few drinks."
Although No Use For A Name is a relatively obscure band to some, they have carved out a devoted following over more than two decades. They toured the country when The Warped Tour was still in its infancy and released a greatest hits collection in 2007 titled "All The Best Songs."
Music sites and social media saw an outpouring of mourning Wednesday immediately after the news broke. "Tony Sly" was trending nationally due in part to tweets like "Sad news, RIP Tony Sly, Easily one of the best," from @TheeSocials .
"RIP Tony Sly. Will be listening to No Use for A Name tonight" from @cecil_90210 is another tweet that was typical Wednesday. Unlike almost every other topic on social media, memories of the singer have been almost entirely positive.