If I have a judgement on someone filing bankruptcy, can I file for a claim on his current employment wages?

For a standard civil judgment, if he's already filed, then almost certainly not. An "automatic stay" is instituted upon filing for bankruptcy, and all legal actions against the debtor are suspended. You'd have to make your claim through the bankruptcy trustee. If the bankruptcy is no-asset, then there would likely be nothing for your claim and it would be extinguished upon discharge of the bankruptcy.