Wes Scantlin ARRESTED -- Puddle of Mudd Singer Busted for Domestic Violence

Puddle of Mudd singer Wes Scantlin was arrested in L.A. last night after cops say he roughed up his ex-wife in front of several witnesses ... TMZ has learned.

Law enforcement sources tell us ... police were called to a business in West Hollywood around 3:30 pm after someone reported Scantlin shook his ex-wife and then tried to drag her by the arm or the shirt.

When cops arrived ... we're told deputies spoke with witnesses and the victim -- and decided to arrest Scantlin for domestic violence.

We're told Scantlin was extremely uncooperative during the arrest -- one source tells us, "He was very mouthy."

Sources tell us Scantlin -- who penned the hits "She Hates Me" and "Blurry" -- is currently in custody and bail has been set at $20,000.